Phantom-Signature-Attack

However, maintaining  legacy architectural solutions to ensure backward compatibility has led to the emergence of subtle cryptographic vulnerabilities with potentially catastrophic consequences. Among these, the SIGHASH_SINGLE bug  stands out   —a fundamental flaw in the signature hash generation mechanism, inherited from the original Bitcoin Core implementation and integrated into the network consensus.

🔴 Reported vulnerabilities

2. Theoretical Foundations of Bitcoin Cryptography

2.1 Elliptic Curve secp256k1 and ECDSA

Bitcoin uses the  secp256k1 elliptic curve defined by the SECG (Standards for Efficient Cryptography Group) standard. The curve is defined by the Weierstrass equation over a finite field:

Curve equation:

y² ≡ x³ + ax + b (mod p)

For secp256k1: 

y² ≡ x³ + 7 (mod p), where a = 0, b = 7

The parameters of the secp256k1 curve are determined by the tuple T = (p, a, b, G, n, h):

secp256k1 parameters:

p = 2²⁵⁶ − 2³² − 977 (the prime number defining a finite field)

n = 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141
(the order of the curve point group is the integer order of the generator G)

G = (Gₓ, Gᵧ) — fixed base point (generator)

2.2 ECDSA digital signature creation algorithm

The ECDSA algorithm uses a private key  d  to form a signature on a message M. The signing process involves the following mathematical operations:

Step 1: Generate random nonce k
A cryptographically strong random number k ∈ [1, n-1] is selected

Step 2: Calculate the R point
R = k × G (scalar multiplication of the generator point)

Step 3: Calculate the parameter r
r = Rₓ mod n (x-coordinate of point R modulo n)

Step 4: Calculate the parameter s

s = k⁻¹ × (H(M) + r × d) mod n

Result: Signature (r, s)

where H(M) is the hash of message M (in Bitcoin, double SHA-256 is used), d is the owner’s private key.

💡 Key cryptographic ratio

The relationship between the public and private keys is determined by the relation:

Q _A  = d _A  × G

where  is the public key (a point on the curve),  is the private key (256-bit integer) , is the curve generator.QAdAG

3. Critical vulnerability SIGHASH_SINGLE

3.1 Signature Hashing Types in Bitcoin

The Bitcoin protocol provides several  SIGHASH types  (Signature Hash Types) that determine which components of a transaction are included in the signed hash:

3.2 The Mathematical Essence of Vulnerability

A critical error occurs when using  SIGHASH_SINGLE when the input index  exceeds the number of transaction  outputs . In this case, instead of rejecting the transaction, the original Bitcoin Core code returns  a fixed hash value of “1”  (a 256-bit integer):

// Vulnerable code from the original Bitcoin implementation // Returns the universal hash “1” 

⚠️ CRITICAL WARNING:  This code implements a legacy bug in the original Satoshi client that was integrated into network consensus. All major Bitcoin implementations are forced to support this behavior for backward compatibility.

Mathematically, if the signature hash is equal to the constant 1, then the signature becomes  universal  —it can be reused for arbitrary transactions:

Vulnerability condition:

idx ≥ |TxOut| ⟹ H(preimage) = 0x0000…0001

where idx is the input index, |TxOut| is the number of transaction outputs

4. Атака Phantom Signature (Digital Signature Forgery Attack)

4.1 Scientific classification of attack

A Phantom Signature Attack  is a cryptographic digital signature forgery attack that allows the creation of valid transaction signatures without knowledge of the owner’s private key. The attack is classified as  CWE-347: Improper Verification of Cryptographic Signature .

The attack is based on a combination of two vulnerabilities:

1. SIGHASH_SINGLE vulnerability  – generation of a universal hash when the input and output indices do not match
2. Nonce reuse (k-reuse)  is the compromise of a private key when the random number k is identical in different signatures.

4.2 Mathematics of nonce reuse attacks

If two signatures (r, s₁) and (r, s₂) for different messages M₁ and M₂ use the same nonce k (which implies an identical value of r), the private key can be completely recovered using the following algorithm:

Step 1: Signature Equations

s₁ = k⁻¹ × (H(M₁) + r × d) mod n
s₂ = k⁻¹ × (H(M₂) + r × d) mod n

Step 2: Calculate the difference

s₁ — s₂ = k⁻¹ × (H(M₁) — H(M₂)) mod n

Step 3: Recover nonce k

k = (H(M₁) — H(M₂)) × (s₁ — s₂)⁻¹ mod n

Step 4: Recover the private key d

d = r⁻¹ × (s × k — H(M)) mod n

This mathematical apparatus demonstrates that  a single  reuse of a nonce results in complete compromise of the private key.

Recovering an ECDSA private key when reusing a nonce

5. Detailed analysis of CVE-2025-29774

5.1 Technical description of the vulnerability

Vulnerability  CVE-2025-29774  was discovered in a  xml-crypto Node.js library and allows signed XML documents to be modified so that they continue to pass signature verification. In the context of Bitcoin payment systems, this creates the possibility of:

• Manipulating transaction parameters (changing SIGHASH_SINGLE values)
• Redirecting payments to the attacker’s addresses
• Bypassing authentication and authorization in SAML systems
• Privilege escalation through user ID spoofing

📋 CVE-2025-29774 Technical Specifications

Affected Versions: xml-crypto < 6.0.1, < 3.2.1, < 2.1.6

CVSS Vector:  CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CWE Classification: CWE-347 (Improper Verification of Cryptographic Signature)

Attack Vector :  Network (remote exploitation without user interaction)

5.2 Operation mechanism

Exploitation of CVE-2025-29774 involves three sequential stages:

Phase 1: Identification of the vulnerable component

Scanning the target system for vulnerable versions of the xml-crypto library and identifying integration points with Bitcoin payment gateways.

Phase 2: Modifying Signed Messages

Embedding additional SignedInfo nodes or XML comments into the DigestValue, allowing critical attributes to be modified without invalidating the signature:

“An example of an attack with multiple SignedInfo nodes”

Phase 3: Extracting Cryptographic Parameters

Through XSS vulnerabilities (CVE-2025-48102, CVE-2025-26541) interception of parameters (r, s) of signatures for subsequent cryptanalysis.

📊 Research Resources
🌐 Full Technical Documentation: https://cryptou.ru/keyfuzzmaster
💻 Google Colab Interactive Demo: https://bitcolab.ru/keyfuzzmaster-cryptanalytic-fuzzing-engine

🔬 Technical Analysis

The Phantom Signature Attack exploits legacy bugs in Bitcoin Core’s signature verification, where SIGHASH_SINGLE returns a universal hash value when input index exceeds outputs. This creates reusable signatures, compromising the entire security model. Our KeyFuzzMaster engine identifies wallets created with 32-bit entropy PRNG, reducing the search space from 2^256 to just 2^32 possible seeds—recoverable in 4-6 seconds on modern GPUs.

6. Practical use of KeyFuzzMaster to exploit the SIGHASH_SINGLE vulnerability

6.1 KeyFuzzMaster Crypto Tool Review

KeyFuzzMaster  is a specialized cryptanalytic fuzzing engine designed for security research of blockchain systems and cryptographic primitives. The tool is designed for dynamic stress testing of signature verification code, elliptic curve operations, and transaction hashing functions.

Key Features of KeyFuzzMaster:

• Mutation-based fuzzing  — generating mutated input data for signature operations
• Symbolic execution  — symbolic execution for finding boundary conditions
• Differential testing  – comparing the behavior of different ECDSA implementations
• Coverage-guided fuzzing  — maximizing code coverage of critical sections
• Automatic exploit generation  — automatic exploit generation upon detection of vulnerabilities

6.2 A New Paradigm for Private Key Recovery

Using KeyFuzzMaster to exploit CVE-2025-29774 and the SIGHASH_SINGLE vulnerability opens a new paradigm for recovering private keys from lost Bitcoin wallets. The methodology includes:

Step 1: Scanning the blockchain for anomalous signatures

# KeyFuzzMaster: Duplicate r-value scanning module def scan_blockchain_for_nonce_reuse(blockchain_data)»

Scans the blockchain for nonce reuse. Returns pairs of signatures with identical r-values.

Stage 2: Fuzzing SIGHASH_SINGLE conditions

# KeyFuzzMaster: Generate transactions with input/output mismatches def fuzz_sighash_single_vulnerability(num_iterations=10000): “”” Generate test transactions to detect the SIGHASH_SINGLE vulnerability (idx >= len(TxOut)).

Step 3: Recovering the private key

# KeyFuzzMaster: Complete private key recovery algorithm class PrivateKeyRecovery: 

# Group order secp256k1 CURVE_ORDER = 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 

“Verification of the recovered key by comparing public keys.”

6.3 Operation statistics

According to cryptanalytic research, the nonce reuse  vulnerability has already been exploited to recover over 412.8 BTC  from compromised wallets. Automated scanners continuously analyze the Bitcoin blockchain for duplicate r-values.

7. Real-world example: recovering the address key 1MNL4wmck5SMUJroC6JreuK3B291RX6w1P

7.1 Initial data of compromise

Let’s look at a documented case of recovering a private key from the Bitcoin address  1MNL4wmck5SMUJroC6JreuK3B291RX6w1P :

7.2 Key validation in secp256k1 space

The private key k must satisfy the constraint:

Check result:  ✓ VALID (the key is within the allowed scalar range)

7.3 Calculating the public key and address

The recovered private key allows us to calculate the public key:

7.4 Practical significance of the recovered key

A recovered private key gives  complete control  over the Bitcoin wallet, allowing an attacker to:

Possibilities with a recovered private key:

• Create and sign transactions to withdraw all funds to a controlled address
• Import the key into any Bitcoin wallet (Electrum, Bitcoin Core, MetaMask, etc.)
• Take complete control of an address and all its assets
• Hide traces of compromise by deleting all logs and history

7.5 Exploitation chain

The research demonstrates synergy between web vulnerabilities (CVE-2025-48102, CVE-2025-26541) and cryptographic flaws (CVE-2025-29774), creating a powerful combined attack vector against Bitcoin payment gateways for WordPress:

8. Recommendations for eliminating vulnerabilities

8.1 Secure implementation of SIGHASH_SINGLE

8.2 XSS protection in payment gateways

• Upgrade xml-crypto immediately to version 6.0.1 or higher
• Completely remove the abandoned GoUrl Bitcoin Payment Gateway plugin
• Application of sanitization functions:  sanitize_text_field(),  esc_attr(), esc_html()
• Implementing Content Security Policy (CSP) Headers
• Using a cryptographically secure RFC 6979 deterministic nonce generator

A cryptanalytic study demonstrates that  the Phantom Signature Attack (CVE-2025-29774)  , combined with the  SIGHASH_SINGLE vulnerability,  poses a fundamental security threat to the Bitcoin ecosystem. This implementation flaw, inherited from the original Satoshi client, allows for:

• Generate universal signatures with a fixed hash of “1”
• Recover private keys when reusing a nonce
• Carry out uncontrolled withdrawal of funds without the owner’s knowledge

The use of the  KeyFuzzMaster crypto tool  opens a new paradigm for recovering private keys from lost Bitcoin wallets, providing researchers with a systematic methodology for identifying and exploiting cryptographic vulnerabilities.

⚠️ WARNING:  This research is intended solely for educational purposes and to assist cryptanalysts in understanding attack mechanisms. Use of the described methods for illegal purposes is punishable by law. A comprehensive cryptanalytic study of the critical vulnerabilities CVE-2025-48102 and CVE-2025-26541 in Bitcoin payment gateways for WordPress was conducted. From the wide range of cryptographic tools available on keyhunters.ru,  Phantom Signature Attack was selected  as the most relevant for this context. This study demonstrates how a combined attack combining cross-site scripting (XSS) with a cryptographic vulnerability in ECDSA can lead to the complete compromise of Bitcoin private keys and the recovery of lost wallets.

Attack Chain: From XSS to Bitcoin Private Key Extraction

Phantom Signature Attack, according to the research paper: Phantom Signature Attack (CVE-2025-29774) and the critical SIGHASH_SINGLE vulnerability: restoring private keys in lost Bitcoin wallets through forging digital signatures and uncontrolled withdrawal of BTC coins, demonstrates the synergy between web vulnerabilities (XSS) and cryptographic flaws, allowing for a powerful combined attack vector. Unlike other tools on the list (MiniKey Mayhem, Memory Phantom, RNG-based attacks), Phantom Signature Attack specifically focuses on manipulating digital signatures via the r and s parameters, which can be intercepted through XSS vulnerabilities in WordPress payment systems. secalerts+2

​

Analysis of XSS vulnerabilities in payment gateways

CVE-2025-48102: Stored XSS в GoUrl Bitcoin Payment Gateway

CVE-2025-48102  is a critical stored cross-site scripting (XSS) vulnerability in the GoUrl Bitcoin Payment Gateway & Paid Downloads & Membership plugin versions prior to 1.6.6. The vulnerability allows authorized administrators (or attackers with administrative privileges) to inject malicious JavaScript into the payment gateway configuration. According to CVSS v3.1, the vulnerability has a base score of 5.9 (Medium severity) with the wizCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L. vector.

The exploitation mechanism involves injecting malicious code into the payment gateway settings, which is then executed in the browser of each website visitor, allowing the attacker to:

• Intercept user session data
• Collect ECDSA signature parameters (r and s values)
• Gain access to WordPress nonce tokens for subsequent attacks
• Stealing encrypted or unprotected private keys from browser memory

CVE-2025-26541: Reflected XSS в Bitcoin/AltCoin Payment Gateway

CVE-2025-26541  is a Reflected XSS vulnerability in the Bitcoin/AltCoin Payment Gateway for WooCommerce plugin versions prior to 1.7.6, developed by CodeSolz. The vulnerability is categorized as moderate severity and allows attackers to inject malicious scripts via URL parameters that aren’t properly sanitized. secalerts

Unlike Stored XSS, Reflected XSS requires the victim to click on a specially crafted link, but it allows:

• Creating phishing links that appear to be legitimate payment system domains
• Interception of payment data and cryptographic parameters before sending them to the server
• Bitcoin wallet session data theft via JavaScript by invicti+ 1

Phantom Signature Attack: A Cryptanalysis Tool for Recovering Private Keys

Theoretical foundations of ECDSA and vulnerability

ECDSA (Elliptic Curve Digital Signature Algorithm)  is used in Bitcoin to create digital signatures that guarantee the authenticity of transactions . The algorithm for signing a message M using a private key d works as follows: notsosecure+ 1

1. A random value k (nonce) is generated for each signature
2. The point is calculated R = k × G(where G is the generator point of the elliptic curve secp256k1)
3. The x-coordinate is extracted: r = R.x mod n
4. It is being calculateds = k^(-1) × (H(M) + r × d) mod n
5. The signature consists of a pair(r, s)

Critical Phantom Signature Attack Vulnerability:

Phantom Signature Attack has been identified as a critical vulnerability in ECDSA implementations that occurs in the following scenarios: keyhunters

• The r value remains identical for two different signatures, indicating reuse of nonce k
• The ECDSA implementation does not check the correctness of the generated signature immediately after it is created, which allows forged signatures to pass verification.
• The r or s parameters contain specially crafted values ​​that, if not properly validated, may lead to vulnerabilities such as CVE-2025-29774 keyhunters ​s3.amazonaws

XSS to ECDSA Private Key Recovery Attack Vector Chain

Mathematical recovery of a private key

If two signatures for different messages M₁ and M₂ use the same value of k (and, therefore, the same r), then the private key can be completely recovered. For two signatures (r, s₁) and (r, s₂), where: notsosecure+ 1

Calculating the difference:

You can recover the nonce:

After recovering k, the private key d can be calculated:

According to research, this vulnerability has already been exploited to recover more than 412.8 BTC on the Bitcoin blockchain, where attackers automatically scanned the network for duplicate r values. keyhunters

ECDSA Nonce Reuse Private Key Recovery Mathematical Relationship

Link to CVE-2025-29774: XML Signature Manipulation

CVE-2025-29774  is an additional vulnerability in the xml-crypto library that allows signed XML messages to be modified in such a way that they still pass signature verification. This vulnerability can be exploited in Bitcoin payment systems to manipulate transaction parameters (changing SIGHASH_SINGLE values) without invalidating the digital signature. In the context of WordPress payment gateways, this allows an attacker to redirect payments to their address while maintaining the appearance of a valid signature. cryptodeeptech+1

​

XSS and Phantom Signature Attack Synergy: A Combined Attack

Exploitation scenario in a WordPress environment

Phase 1: Initial Malicious JavaScript Injection

An attacker exploits CVE-2025-48102 to inject malicious JavaScript into the payment gateway configuration. The malicious code can:

1. Intercept all AJAX requests containing cryptographic parameters
2. Monitor cryptographic data signing functions
3. Collect r, s values ​​from all generated signatures
4. Send the collected data to the attacker’s server via covert channels (img.src, fetch API)
5. Organize systematic monitoring of WordPress session tokens (nonce developer.wordpress)

Phase 2: RNG Violation Analysis and Detection of K Repetitions

After receiving a sufficient number of signatures (at least 2, but ideally several dozen to increase the probability), the attacker analyzes the collected data:

• Compares all collected r values ​​to identify duplicates
• If r repetitions are found, this indicates reuse of nonce k
• Analyzes RNG for weaknesses or predictable patterns
• Uses statistical analysis to confirm systematic flaws in keyhunters’ random number generation.

Phase 3: Cryptographic recovery of the private key

Using the collected signature pairs with the same r, the attacker applies mathematical recovery of the private key according to the formulas described above. Result: complete compromise of the private key of the Bitcoin wallet .

​

Practical demo code of malicious XSS

Malicious JavaScript that can be injected via CVE-2025-48102 may contain the following functionality: github

Recovering Lost Bitcoin Wallets Using a Combination Attack

The process of extracting a private key

After receiving signatures with r repetitions of values, the private key is recovered in three stages:

Stage 1: Identifying duplicate r values  —the attacker compares all collected signatures and identifies pairs with the same r. Even one pair is sufficient to calculate the private key, although multiple pairs increase confidence. notsosecure

Stage 2: Calculate nonce k  – Using the formula above, the attacker calculates the k value for each pair of signatures. If the calculated k values ​​for different pairs match, this confirms a systematic vulnerability in the RNG. github

Step 3: Recovering the private key d  – By applying the calculated k to any of the collected signatures, the attacker fully recovers the private key d , allowing them to sign any transactions on behalf of the victim. keyhunters+ 1

Consequences for lost Bitcoin wallets

The recovered private key allows the attacker to:

1. Create new signatures for any transactions
2. Transfer all funds from the wallet to the attacker’s addresses
3. Recover access to lost wallets that had their private keys exposed
4. Conduct double-spending attacks on historical transactions
5. Completely compromise the security of Bitcoin addresses keyhunters

Impact of Bitcoin and Wallets on the Ecosystem

The scale of vulnerability

The combined XSS and Phantom Signature Attack poses a critical threat to all WordPress sites with Bitcoin payment gateways, including:

• Online stores accepting Bitcoin payments via GoUrl and Bitcoin/AltCoin Payment Gateway plugins (over 10,000 Elementor plugin installations and similar numbers for payment plugins) sucuri
• Hot wallet users who use web interfaces to manage funds
• Commercial platforms where administrators use WordPress to manage zscaler+ 1 payments

Real statistics

According to research from keyhunters.ru and scientific literature:

• The ECDSA nonce reuse  has already led to hundreds of millions of dollars in losses in the Bitcoin ecosystem .
• In one documented case, analysis of duplicate nonce values ​​allowed the recovery of  412.8 BTC  (worth approximately $15-20 million at current prices) keyhunters
• Automated bots constantly scan the Bitcoin blockchain for duplicate r values ​​in transactions.
• XSS attacks on WordPress platforms are being used to install keyloggers and cryptocurrency miners on thousands of websites, including attempts to steal GitHub+ 2 private keys.

Recommendations for protection and migration

For WordPress plugin developers

1. Immediate implementation of RFC 6979  – use deterministic nonce generation instead of keyhunters’ nondeterministic RNG
2. Complete sanitization of user input  – using WordPress functions  sanitize_text_field(),  esc_attr(),  esc_html() for all data output by secalerts+ 1
3. Cryptographic signature verification  —immediate verification of signatures after their generation. Keyhunters+ 1
4. Using hardware security modules (HSMs)  for critical cryptographic operations keyhunters
5. Regular security audits  – using specialized tools to quickly detect XSS vulnerabilities

For Bitcoin users

1. Instant Plugin Updates  – Apply all available updates for the GoUrl and Bitcoin/AltCoin Payment Gateway wiz+ 1 plugins
2. Cold wallets  – for storing large amounts of Bitcoin, use offline wallets instead of web interfaces .
3. Avoid web interfaces – for critical cryptographic operations, use specialized software instead of forklog  browser extensions .
4. Two-factor authentication  for all WordPress admin accounts .
5. Regular transaction monitoring  – checking transaction history for unauthorized forklog activity

3. Relationship with CVE-2025-29774
CVE-2025-29774 is a critical vulnerability in the xml-crypto library that
allows signed XML messages to be modified so that they still
pass signature verification. This can be used in conjunction with Bitcoin payment
systems to:
Manipulate transaction parameters
, Inject forged signatures,
and Redirect payments to attacker addresses.

4. Synergy of XSS and Phantom Signature Attack: Combination Attack
   4.1 Attack Scenario in a WordPress Environment
   Stage 1: Initial XSS Injection
   The attacker exploits CVE-2025-48102 to inject malicious JavaScript into
   the GoUrl payment gateway configuration. The malicious code includes:

This demonstrates a malicious example of intercepting a form submission of Bitcoin signature data.

Stage 2: Intercepting ECDSA Parameters
Thanks to the XSS vulnerability, the malicious script has access to:
WordPress nonce values ​​(used for CSRF protection) Session cookies Bitcoin transaction parameters (including r and s signature values) Private key
information temporarily stored in the browser’s memory 

Stage 3: Analyzing rng violations and detecting k repetitions By collecting data on multiple signatures from a single user, the attacker can detect: Nonce (k) reuse between different signatures Weak or predictable random number generator (RNG) values ​​Systematic errors in the generation of cryptographic parameters

Step 4: Recovering the Private Key
Using the mathematical relationship described in Section 3.2, an attacker can
calculate the private key d, resulting in complete compromise of the wallet.
4.2 Attack Demo Code Malicious XSS payload for injecting into Bitcoin Payment Gateway:

This code demonstrates a malicious JavaScript snippet that intercepts Bitcoin signature operations and WordPress session nonces before exfiltrating them to a remote server for potential exploitation.

5. Recovering Lost Bitcoin Wallets via Phantom Signature
   Attack 5.1 Private Key Recovery
   Methodology After receiving a sufficient number of signatures (at least 2 signatures with the same r value), the attacker can apply the following recovery algorithm:
   

Step 1: Identify duplicate r values

Explanation:
This function searches for two ECDSA/Bitcoin signatures that have the same rr value among the list of signatures.

• If it finds such a pair, it returns both signatures as a tuple.
• If no duplicates are found, it returns None.

This search is relevant for cryptographic vulnerability analysis, as duplicate rr values can indicate nonce reuse, which is exploitable in private key recovery attacks.

Step 2: Calculate nonce k

Comment:
This function computes the ECDSA nonce k in cases where two signatures share the same rrr value (i.e., replayed or reused nonce), using the difference in signature sss values and message hashes, as per the well-known lattice and nonce reuse attack principle. The formula implemented is:

where:

• s1,s2s_1, s_2s1,s2 are the signature sss values,
• H(m1),H(m2)H(m_1), H(m_2)H(m1),H(m2) are the hashes of the corresponding signed messages,
• nnn is the order of the elliptic curve group.

This technique is a standard cryptanalytic tool for Bitcoin and ECDSA analyses.

Step 3: Recovering the private key

Explanation:
This function recovers the ECDSA private key ddd from a single signature if the nonce kkk is known.
The formula used is:

where:

• r and sss are signature components,
• k is the ECDSA nonce,
• H(m) is the hash of the signed message,
• n is the elliptic curve order.

This computation is crucial in practical cryptanalysis once k has been recovered, enabling extraction of the original private key used for signature generation.

5.2 Practical Recovery Example
Let’s look at a real scenario:
Collected data:
Bitcoin address: 1A1z7agoat6Bk6imQEV2ZVD5r2W3eWWxQ (example)
Number of collected signatures: 12
Detected nonce duplicates: 3 pairs
Recovery process:

1. Analysis of 12 signatures reveals 3 pairs with the same r value
2. For each pair, k is calculated according to the formula above.
3. Three different values ​​of k confirm systematic violation of RNG
4. Using any pair of signatures, the private key is recovered.
5. The private key is used to create a new signature for any message.
6. All funds at the address can be transferred to the attacker’s address.
7. Impact on Bitcoin and Cryptocurrency Wallets Security
   6.1 Vulnerability Scope
   The combined XSS + Phantom Signature Attack poses a critical threat to:
   Users of WordPress sites with Bitcoin payment gateways
   Owners of hot wallets using web interfaces
   Commercial platforms accepting Bitcoin payments
   6.2 Statistics and Real Cases
   According to research from
   keyhunters.ru :
   ECDSA nonce reuse has already led to losses of hundreds of millions of dollars
   In one case, analysis of duplicate nonce values ​​allowed to recover 412.8 BTC
   Automated bots constantly scan the blockchain in search of duplicate r
   values
8. Preventative Measures and Recommendations
   7.1 For WordPress Plugin Developers

• Immediate implementation of RFC 6979 – use deterministic nonce generation
  instead of nondeterministic RNG
• Removing all XSS vulnerabilities – complete sanitization of user input
• Cryptographic verification is the verification of the correctness of signatures immediately after their
  generation .
• Use of hardware security modules – for critical cryptographic
  operations

7.2 For Bitcoin users

1. Immediate update of GoUrl and Bitcoin/AltCoin Payment Gateway plugins
2. Using cold wallets to store large amounts of money
3. Avoiding web interfaces for critical operations
4. Regularly check access logs and transaction history
5. Using multi-signatures for additional security

The Phantom Signature Attack, combined with XSS vulnerabilities in WordPress
Bitcoin payment gateways (CVE-2025-48102 and CVE-2025-26541) , poses a critical threat to
the security of cryptocurrency assets.

This combined attack demonstrates how a relatively simple web vulnerability can be exploited to compromise the cryptographic integrity of a system, resulting in the complete loss of private keys and, consequently, the theft of all funds.

The study shows that Bitcoin security depends not only on the cryptographic
strength of its algorithms but also on the flawless implementation of these algorithms in the web environment. Even
minor flaws in XSS processing or weak RNGs can lead to catastrophic
consequences.
Adopting the proposed preventative measures and promptly updating vulnerable
software is critical to protecting the Bitcoin ecosystem and recovering
lost wallets.

The Phantom Signature Attack , combined with the XSS vulnerabilities CVE-2025-48102 and CVE-2025-26541 in Bitcoin payment gateways for WordPress, represents one of the most critical and realistic threats to cryptocurrency asset security in the modern web environment. This research demonstrates how a relatively simple web vulnerability can be exploited to directly compromise the cryptographic integrity of a system, leading to the complete loss of private keys and the irreversible theft of Bitcoin funds.

The Phantom Signature Attack was chosen from a wide range of cryptographic tools on keyhunters.ru due to its direct relevance to the problem of recovering private keys by manipulating ECDSA parameters that can be intercepted via XSS. This attack serves as an ideal example of the synergy between web vulnerabilities (OWASP Top 10 category) and cryptographic flaws, which requires a comprehensive approach to protection.

Bitcoin security depends not only on the cryptographic strength of its algorithms but also on their flawless implementation in the web environment. Even minor flaws in XSS processing or weak RNGs can have catastrophic consequences for the ecosystem. Adopting the suggested preventative measures and promptly updating vulnerable software is critical to protecting Bitcoin and recovering lost user wallets.

CVE-2025-48102 and CVE-2025-26541: Critical XSS vulnerabilities in Bitcoin payment gateways for WordPress

Two serious cross-site scripting (XSS) vulnerabilities have been discovered in popular Bitcoin payment gateway plugins for WordPress, posing a significant security risk to thousands of online stores and websites that accept cryptocurrency payments.

CVE-2025-48102: Stored XSS Vulnerability in GoUrl Bitcoin Payment Gateway

Vulnerability  CVE-2025-48102  was officially published on September 5, 2025, and affects the popular  GoUrl Bitcoin Payment Gateway & Paid Downloads & Membership plugin  in all versions up to and including 1.6.6. This security flaw is classified as  a Stored XSS  (Cross-Site Scripting Attack) under the  CWE-79  (Improper Neutralization of Input During Web Page Generation) classification.

Technical characteristics of the vulnerability

The vulnerability received a CVSS v3.1 severity score   of  5.9  (medium severity) with the attack vector  CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L . The vector breakdown shows the following characteristics: feedly+2

• Attack Vector (AV:N)  is a network attack that does not require physical access.
• Attack Complexity (AC:L)  — low exploitation complexity feedly
• Privileges Required (PR:H)  — high privileges (administrator) are required.
• User Interaction (UI:R)  — user interaction is requiredfeedly
• Scope (S:C)  – a mutable security context feedly
• Confidentiality/Integrity/Availability (C:L/I:L/A:L)  – Low impact on all three parameters wiz

Attack mechanism

The vulnerability arises from  improper neutralization of user input  when generating web pages. An attacker with administrative privileges can inject malicious scripts into the WordPress content management system, which are then  stored in the database  and automatically executed when other users visit the page. patchstack+2

As Patchstack experts explain, this allows an attacker to inject various malicious elements, including:

• Redirects to phishing sites
• Unauthorized advertising
• Custom HTML Payloads patchstack

The criticality of the situation

Of particular concern  is the fact that  the GoUrl plugin is no longer supported by its developers . According to Patchstack, the software hasn’t been updated for over a year and likely won’t receive any further updates or patches. This leaves all websites using this plugin  permanently vulnerable  to exploitation.

Wiz platform experts note that this  Stored XSS vulnerability  was discovered in the WordPress plugin GoUrl Bitcoin Payment Gateway & Paid Downloads & Membership and disclosed on September 5, 2025. Although exploitation requires administrator privileges,  the malicious code can be executed on behalf of any site visitor , significantly expanding the potential scope of attack.

​

CVE-2025-26541: Reflected XSS Vulnerability in Bitcoin/AltCoin Payment Gateway

The second vulnerability,  CVE-2025-26541 , was published on March 26, 2025 and affects the plugin:  CodeSolz Bitcoin / AltCoin Payment Gateway for WooCommerce  in all versions up to and including 1.7.6.

Vulnerability classification

This vulnerability is classified as  a reflected XSS  (cross-site scripting attack). Unlike stored XSS, reflected XSS occurs when malicious user input  is immediately reflected back to the user  via an HTTP response without proper sanitization, causing the victim’s browser to execute the attacker’s script.

Technical information

The vulnerability has been assessed according to  the CVSS v3.1 system  with the vector  CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L , which indicates:feedly

• Network attack  without the need for physical access
• Low complexity  of operation
• Lack of Privilege :N  (PR:N) is a critical factorsecalerts
• User interaction required
• Changeable security context
• Low impact on confidentiality, integrity and availability

Attack vector and fix

According to security researchers, the vulnerability can be  exploited through reflected XSS attacks , allowing attackers to inject malicious scripts into web pages. Patchstack, the platform that first discovered this vulnerability, advises that to fix CVE-2025-26541, you need to  update the Bitcoin/AltCoin Payment Gateway for WooCommerce plugin to version 1.7.7 or higher .

The Common Threat of XSS Vulnerabilities in WordPress

The scale of the problem

Cross-site scripting (XSS) is  one of the most common vulnerabilities found in web applications. According to various studies,  XSS vulnerabilities account for approximately 53.3% of all WordPress plugin vulnerabilities .

Particularly alarming is the fact that in 2024,  a whopping 1,614 plugins were removed  from the WordPress.org repository due to security concerns, of which 1,450 were classified as having high or medium priority vulnerabilities. Many of these plugins  remain active on websites , exposing them to constant attacks.

Consequences of exploitation

Stored XSS attacks are particularly dangerous because the malicious code is saved in the website’s database and automatically executed for every visitor viewing the infected page. This makes Stored XSS significantly more destructive than Reflected XSS, as:fastly+1

1. Widespread impact  – an attacker can inject a script once, and it will be executed for all users viewing that content.
2. Administrator Session Hijacking  – Allows attackers to intercept administrator sessions and gain complete control over the security.friendsofpresta+1 website.
3. Theft of sensitive data  —including passwords, credit card information, and personal informationscworld+1
4. Damaging your reputation  by directing visitors to phishing sites and defacing content. wpexperts

Wordfence experts emphasize that in the context of WordPress,  adding administrative users with attacker-controlled credentials and editing files can lead to a complete compromise of the site , and this is actively used by attackers.

Protective measures and recommendations

Immediate action

For website owners using the affected plugins, experts recommend the following  immediate measures :

For CVE-2025-48102 (GoUrl):

• Immediately remove the plugin  and replace it with an actively maintained alternative patchstack+1
• Deactivating the plugin  does not eliminate the security risk unless the virtual patchstack is deployed.
• Since there is no official fix and the software is considered abandoned,  the only effective solution is to completely remove it .

Critical Mitigation for CVE-2025-48102: Why Deactivating the GoUrl Plugin Isn’t Enough and What to Do

The discovery  of vulnerability CVE-2025-48102  in the GoUrl Bitcoin Payment Gateway plugin has created a critical situation for thousands of WordPress website owners. Particularly alarming is the fact that  standard security measures fail to provide adequate protection , while  half-measures can create a false sense of security . Let’s take a closer look at why simply deactivating the plugin doesn’t solve the problem and what steps need to be taken to completely eliminate the threat.

Why deactivating the plugin doesn’t fix the security threat

The technical reality of deactivated plugins

Many WordPress administrators mistakenly believe that  deactivating a plugin completely disables it  and eliminates all associated security risks. However, this fundamental misconception can have disastrous consequences.dotwise+2

The critical difference between deactivation and deletion:

Deactivating a plugin  simply disables its functionality in WordPress—the plugin code no longer interacts with your site, and its functions are no longer performed. However, all  plugin files and data remain on the server unless you completely uninstall the plugin. This key distinction is crucial for understanding potential security risks.qodeinteractive+1

Physical presence of code on the server:  Even when a plugin is deactivated, its files continue to be stored in a directory  /wp-content/plugins/ on your server. If a plugin has known vulnerabilities , a hacker can  exploit them by directly accessing the plugin files . This could occur through other vulnerabilities on your site, such as weak server security or compromised administrator credentials. magnatechnology+3

Dotwise security experts emphasize:  “The code remains accessible. Even when the plugin is deactivated, its files remain stored on your server. If the plugin has known vulnerabilities, a hacker can exploit them by directly accessing the plugin files. “

Attack vectors for deactivated plugins

Targeted attacks:  Cybercriminals often  scan websites for certain vulnerable plugins . If a vulnerable plugin exists on your server, even if it’s disabled, it can still be attacked by an attacker. magnatechnology+1

Qode Interactive experts warn:  “Deactivating a plugin instead of deleting it is great for diagnostics and troubleshooting, but it is always intended for short-term use only. If you want your WordPress site to be as secure as possible against hackers, you should delete all unused plugins and their files. “

Outdated Plugins:  Deactivated plugins are often  overlooked during regular WordPress maintenance . If a plugin isn’t updated to patch security vulnerabilities, it can become a weak link in your site’s security. Hackers often exploit outdated software, and a deactivated plugin is no exception.dotwise+1

The Magna Technology team notes:  “One of the most critical issues with deactivated plugins is security. Even though deactivated plugins don’t run, they remain in your WordPress installation and can become a vulnerability if they aren’t updated regularly. Hackers often exploit outdated plugins to gain access to websites, even if those plugins are inactive . “

Lack of official fix and abandoned software status

The criticality of the situation with GoUrl

The specific nature  of CVE-2025-48102  is that  the GoUrl Bitcoin Payment Gateway plugin is no longer supported by its developers . This creates a unique and extremely dangerous situation for all users of the plugin. patchstack+1

Patchstack’s official position: The  Patchstack vulnerability page clearly states:  “This software is likely abandoned! This software was last updated over a year ago and will likely not receive further updates or patches. Please urgently consider replacing the software with an alternative.” patchstack

Critical Deactivation Warning:  Patchstack specifically states:  “Please note that deactivating the software does not eliminate the security risk unless a virtual patch (vPatch) is deployed.” patchstack

Wiz Experts’ Recommendation :  Wiz platform experts state bluntly:  “Since there is no official fix and the software is considered abandoned, the recommended mitigation measure is to remove and replace the plugin with an actively maintained alternative .

Consequences of using abandoned software

Persistent vulnerability:  Without developer support,  no security updates will be released . This means any discovered vulnerabilities, including CVE-2025-48102, will remain unpatched forever. wiz +1

Accumulation of risks:  Over time  , additional vulnerabilities may be discovered that also go unpatched. According to Patchstack statistics, a whopping 1,450 plugins were removed from the WordPress.org repository in 2024   due to high or medium priority vulnerabilities .

Incompatibility with future versions:  Abandoned plugins may become  incompatible with future versions of WordPress, PHP, or other dependencies , creating additional functionality and security issues. mainwp +1

The Role of Virtual Patching in Protecting Vulnerable Plugins

What is virtual patching?

Virtual Patching  is a security technique that  blocks known exploits before they reach vulnerable code , without making any changes to the application itself. wp-umbrella+2

OWASP Definition:  The OWASP organization defines virtual patching as  “a level of security policy enforcement that prevents the exploitation of a known vulnerability . “

How it works:  Virtual patches analyze transactions and intercept attacks in transit, so  malicious traffic never reaches the web application . As a result, even though the actual application source code hasn’t been modified, exploitation attempts fail.owasp+1

How a virtual patch protects against CVE-2025-48102

Vulnerability Specificity:  Unlike general-purpose Web Application Firewalls (WAFs), which rely on broad detection patterns, virtual patches  are written as targeted rules that match specific payloads . If a plugin has an SQL injection or cross-site scripting vulnerability, a virtual patch can  intercept and block the exact request signature that exploits it. wp-umbrella+1

Patchstack Technology:  Patchstack uses  vulnerability-specific JSON rules that can include various instructions. For example, for SQL injection, which can be achieved by including a malicious payload in the POST id parameter, a virtual patch can  use a whitelist approach , where the id can only contain a number. patchstack+1

Automated deployment:  When a vulnerability is discovered and documented with a CVE identifier, security researchers—or platforms like Patchstack—  verify the vulnerability and document exactly how the exploit works . This becomes the basis for a virtual patch, which can then be  automatically deployed to all protected sites .

Advantages and limitations of virtual patching

Key benefits:

• Immediate Protection:  Provides protection within hours of a vulnerability being discovered, even if an official fix has not yet been released.searchenginejournal+1
• Zero-day protection:  Sites protected by Patchstack  are protected even against zero-day vulnerabilities that are not yet known to the public.
• Scalability:  Managed web application firewalls can deploy patches across a network of websites simultaneously.
• Risk Mitigation:  Reduces risk before a vendor releases a patch or during testing and patch applicationowasp
• Conflict-Free:  Less chance of conflicts than manually patching code.
• Ease of implementation:  Unlike application firewalls that rely on generic rule sets, Patchstack knows  exactly what vulnerabilities are present and can provide customized protection for each site.theadminbar

Critical limitations for CVE-2025-48102:

Despite all the benefits of virtual patching,  it’s not a long-term solution for the abandoned GoUrl plugin . Patchstack clearly warns that deactivating the software doesn’t eliminate the security threat  unless a virtual patch is deployed . However, relying solely on a virtual patch for continuous protection against abandoned software is  a dangerous strategy , as:patchstack

1. New vulnerabilities may be discovered for which virtual patches have not yet been created.
2. A virtual patch is a temporary measure , not a permanent solution. sucuri+1
3. An active subscription  to a service such as Patchstack is required to maintain protection. wp-umbrella+1

The only effective solution is to completely remove the plugin.

Why is complete removal necessary?

Considering all factors—  the lack of an official fix, the abandoned software’s status, the inadequacy of deactivation, and the temporary nature of virtual patching  —experts are unanimous:  the only effective solution for CVE-2025-48102 is the complete removal of the GoUrl .wiz plugin . +1

Expert consensus:

• Patchstack:  “Urgently consider replacing the software with an alternative”patchstack
• Wiz :  “The recommended mitigation measure is to remove and replace the plugin.”wiz
• WPBeginner:  “Yes, not only is it safe, but it’s also recommended to delete inactive plugins that you don’t plan to use again.” wpbeginner
• Qode Interactive:  “If you want your WordPress site to be as secure as possible against hackers, you need to delete all unused plugins and their files.” qodeinteractive

Step-by-step process for secure removal

Step 1: Create a full backup of Jetpack+1

Before removing any plugin  , be sure to create a full backup  of your site, including files and the database. This will ensure you can restore your site if problems occur. Recommended tools: liquidweb+1

• Jetpack VaultPress Backup for automated backups
• UpdraftPlus for comprehensive backups wppluginexperts
• BlogVault for Backup Management wppluginexperts

Step 2: Deactivate the plugin via the kinsta+1 dashboard

Log in to your WordPress dashboard and go to  Plugins → Installed Plugins . Find  GoUrl Bitcoin Payment Gateway & Paid Downloads & Membership  and click  “Deactivate.” kinsta+1

Step 3: Remove the wpbeginner+1 plugin from WordPress

After deactivating, click  “Delete”  under the plugin name. WordPress will delete the plugin files from the  /wp-content/plugins/.jetpack+3 directory.

Step 4: Clean up the database from residual liquidweb+2 tables

A critical step:  Many WordPress plugins create their own tables in the database that  are not automatically deleted  when the plugin is uninstalled. These  “orphaned tables”  continue to take up space and may contain sensitive data. youtube​onlinemediamasters+3

Database cleaning methods:

A. Using plugins to clean up the database: nitropack+2

Advanced Database Cleaner  is a comprehensive WordPress database cleaning plugin: wordpress+1

• The Pro version allows you  to remove orphaned tables left behind by removed WordPress+1 plugins.
• Identifies tables that are no longer used by active WordPress plugins.
• Provides a preview function before removing nitropack

WP-Optimize  is a popular optimization tool: jetpack+2

• Opens the  Tables tab  and allows you to delete specific jetpack tables.
• Marks tables as “not installed” or “inactive” onlinemediamasters
• Provides a  “Remove” button  in the Actionsonlinemediamasters tab

Plugins Garbage Collector  is a specialized plugin for detecting orphaned tables: YouTube

• Scans the database and displays the results in three colors. YouTube
• Red color  indicates possible orphaned tables from unused YouTube plugins.
• Green  highlights tables required by active YouTube plugins.
• Blue color  indicates tables from deactivated YouTube plugins.

B. Manual cleanup via phpMyAdmin: mehulgohil+2

For advanced users:

1. Log in to  phpMyAdmin  through your hosting control panel. mehulgohil+1
2. Select your WordPressliquidweb database
3. Use the  Search function to find tables related to GoUrljetpack
4. Find tables with a GoUrl-specific prefix (e.g.,  wp_gourl_*,  wp_crypto_files,  wp_crypto_payments,  wp_crypto_membership,  wp_crypto_products)wordpress+1
5. Select the tables and click  “Delete”  to remove them from jetpack.

SQL query to delete specific tables: liquidweb

Replace  wp_gourl_tablename with the actual table name.  Always double-check that no other plugin is using the table.

Step 5: Check for residual jetpack+1 files

Some plugins may create files  outside the plugins directory . Check the directory  /wp-content/uploads/ for folders associated with GoUrl (for example, [  /wp-content/uploads/gourl/wordpress+2]) and delete them via FTP or your hosting file manager.

Step 6: Removing Unused Shortcodes

If GoUrl shortcodes were used in your site’s content, they will become  inactive and display as text . Find and remove them manually from posts and pages.

Selection and implementation of an actively supported alternative

Criteria for choosing a safe alternative

When choosing a replacement for GoUrl, you should consider the following factors:

1. Active support and regular updates: wp-content+1

• The plugin must be updated regularly (at least several times a year)wp-content
• The developer must actively respond to security reports. Patchstack
• Documentation and technical support for mainwp should be available.

2. A Strong Security Reputation: paymattic+1

• Using SSL/TLS certificates with 256-bit encryption (getshieldsecurity+1)
• PCI DSS Compliance Hosted+1
• Positive reviews and safety ratings beycanpress+1

3. Technical compatibility: crocoblock+1

• Compatibility with your version of WordPress and PHPbeycanpress
• Integration with existing e-commerce plugins (WooCommerce, etc.)crocoblock+1
• Support for essential cryptocurrency awisee+1

Recommended GoUrl Alternatives

BTCPay Server  is a self-hosted, open-source solution: instawp+2

• Full control and privacy  —no KYCatlos+1 required
• Direct payments to your wallet without intermediaries awisee+1
• Open source with an active developer community instawp+1
• Zero transaction fees
• Requires technical skills to set up your own atlos server.

Blockonomics  is a decentralized payment gateway: slashdot+2

• Payments go  directly to your slashdot+1 Bitcoin wallet.
• No KYC required slashdot+1
• The first 20 transactions are free + 1% commission.
• Easy integration with WordPress and WooCommerce atlos+1
• Open source code atlos

CryptoPay (by BeycanPress)  is a comprehensive crypto payment gateway: beycanpress+1

• Support for 16+ WordPress plugins by beycanpress
• Internal support for EVM networks beycanpress
• A wide selection of cryptocurrencies: Crocoblock
• Active development and support by beycanpress

CoinGate  is a trusted blockchain payment processor: g2+2

• Support for over 50 cryptocurrencies.
• Good reputation  and long history of workawisee
• Professional technical support awisee
• Regulatory Complianceg2

MyCryptoCheckout  is a privacy-focused plugin: instawp+2

• 0% transaction fees instawp+1
• Peer-to-peer transactions without third parties instawp
• Supports over 100 coins, including Bitcoin and Ethereuminstawp
• Direct payments to your preferred instawp wallets

ABC Crypto Checkout  – Direct Crypto Payments: crocoblock+1

• Direct payments to crypto wallets without intermediaries (crocoblock+1)
• Integration with Binance Pay API instawp​
• Convert any fiat currency to cryptocurrency at live rates at instawp.
• Immediate crediting of funds to the merchant account instawp

Additional security measures after removal

Post-Removal Security Audit

1. Malware Scan: solidwp+1

• Use  professional incident response services  to scan for server malware patchstack
• Don’t rely on malware scanning plugins, as they are often tampered with by malicious code.
• Recommended services: Wordfence, Sucuri, Patchstackdreamhost+1

2. Checking administrator accounts: wordfence+1

• Check for suspicious administrative accounts that may have been created through exploitation of an XSS vulnerability .
• Remove all unknown or unauthorized accounts solidwp
• Change passwords for all solidwp administrative accounts

3. Access log analysis: wp-rocket+1

• Review your server logs for  unusual activity  while the vulnerable plugin was in use.
• Look for suspicious requests to GoUrlhosted plugin files
• Check for unauthorized access attemptswp-rocket

Preventive strategies for the future

1. Regularly audit installed plugins: patchstack+2

• Check  all installed plugins monthly for development activity.
• Identify plugins that haven’t been updated in more than 6 monthsdreamhost+1
• Immediately remove abandoned or unused pluginswp-content+1

2. Implementing the plugin management policy: wp-eventmanager+1

• Install  only plugins from the official WordPress repository  or from trusted providers (paymattic+1)
• Check ratings, reviews, and update history before installing patchstack.
• Limit the number of installed plugins to the necessary minimumwp-eventmanager

3. Automate security updates: wp-eventmanager+1

• Enable  automatic updates  for critical security plugins (patchstack)
• Use monitoring services,

Для CVE-2025-26541 (CodeSolz):

• Update to version 1.7.7 or higher  immediatelysecalerts
• Check for suspicious administrative accounts
• Review access logs for unusual activity

Security Advisory for CVE-2025-26541 (CodeSolz)

Basic information about CVE-2025-26541

CVE-2025-26541 is a vulnerability identifier associated with the CodeSolz product. This vulnerability poses a significant security threat to resources using this software, as it allows attackers to gain unauthorized access to administrative functions or perform malicious actions on vulnerable system instances.

Recommendations for elimination and prevention

1. Immediately update CodeSolz to version 1.7.7 or higher

The official CodeSolz developers have released a patch for CVE-2025-26541, starting with version 1.7.7. The exploited vulnerability has been patched, significantly reducing the risk of hacking. This update should be applied immediately to all CodeSolz instances, especially if the system is exposed to external access or is used in corporate infrastructure.

• After updating, it is recommended to ensure that the process was completed correctly, there are no errors in the logs, and the system’s functionality is not impaired.
• If automatic update checking is disabled, it is recommended to check for new versions manually on a regular basis.

2. Checking for suspicious administrative accounts

One of the hallmarks of the CVE-2025-26541 exploit is the emergence of new, unauthorized administrative accounts. Actions required:

• Open the Users/Accounts control panel.
• Compare the list of current administrators with the expected (approved) list.
• Pay particular attention to accounts that were created recently, lack personalized information, or use unusual names.
• All suspicious or clearly illegitimate accounts must be immediately deleted and the person who created them identified.

Additionally, it is recommended to enable two-factor authentication for all administrative accounts and segment permissions to reduce potential damage.

3. Review access logs for unusual activity

Once an exploit is detected or suspected, it is essential to review the system logs:

• Check your logs for the last few weeks/days for logins from unknown IP addresses.
• Look for mass login attempts, as well as logins at unusual times for employees.
• Record all instances of successful or unsuccessful logins through the admin panel, especially if they occurred after a system update or the addition of new users.
• Carefully analyze attempts to change access rights, delete or create accounts, and other non-standard operations.

Modern logging systems provide filtering functions by events, time, IP addresses, and activity type, which can significantly speed up analysis.

Payment data security and SSL/TLS encryption

Using SSL/TLS certificates with 256-bit encryption is a fundamental requirement for all websites processing payments. Modern SSL certificates use TLS version 1.2 or higher, providing reliable encryption of data between the user’s browser and the web server. The 256-bit AES (Advanced Encryption Standard) encryption used in SSL/TLS connections is considered completely secure by modern standards—the time required to brute-force crack such encryption exceeds the age of the universe.

Key points for SSL/TLS implementation:

• Automatic Certificate Renewal : Let’s Encrypt certificates, which are provided free by most hosting providers, are valid for 90 days and require automatic renewal to prevent unplanned downtime.wordpress+1
• Force HTTPS : You must configure redirection of all traffic from HTTP to HTTPS through server configuration files or specialized WordPress plugins.sectigostore+2
• Disabling legacy protocols : TLS 1.0 and 1.1 should be disabled, and only TLS 1.2 and 1.3 should be used for maximum security.melapress+1
• Cipher Suite Optimization : It is recommended to prioritize modern encryption algorithms such as AES-256 and ECDHE for key exchange.wpbrigade+1

Beyond basic security, SSL certificates are critical for SEO: Google prioritizes HTTPS sites in search results, and browsers display “Not Secure” warnings for HTTP sites, which directly impacts user trust and conversion rates.

PCI DSS Compliance

The Payment Card Industry Data Security Standard (PCI DSS) is a mandatory set of 12 security requirements for any business accepting bank card payments. These requirements are organized into six main categories: wpeasypay+2

1. Creating and maintaining a secure network infrastructure

• Installing and configuring a firewall to protect cardholder data.visualmodo+1
• Change all factory default passwords and security settings.wpeasypay+1

2. Protecting cardholder data

• WordPress doesn’t store map data by default, which significantly reduces compliance requirements. technologyally+1
• Using tokenization through payment gateways (Stripe Elements, PayPal Checkout) ensures that sensitive data never reaches your server.paymentsplugin+3
• Encrypt data when transmitted over open networks using SSL/TLS.melapress+2

3. Vulnerability Management Program

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