Glass Cage: Zero-Click PNG Exploit Chain for iOS 18.2.1

• CVE-2025-43300: O.o.B Wrrite in ImageIO
• CVE-2025-24201: WebKit Remote Code Execution
• CVE-2025-24085: Core Media Privilege Escalation

Patched: Jan-March 2025
Tested On: iPhone 14 Pro Max (iOS 18.2.1)

VirusTotal Analysis (Verified Hash)

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Summary

Glass Cage is a critical, zero-click PNG-based exploit chain discovered in the wild targeting iOS 18.2.1. The attack was actively observed on a compromised device and confirmed to be used against real-world targets prior to vendor patching.

A malicious PNG image sent via iMessage initiates the chain by triggering automatic parsing in MessagesBlastDoorService (CVE-2025-43300). The image exploits a WebKit heap corruption vulnerability (CVE-2025-24201), followed by a sandbox escape and a kernel-level privilege escalation in Core Media (CVE-2025-24085).

The chain ultimately provides attackers with root-level access, persistent control, keychain exfiltration, and even the ability to irreversibly brick devices via IORegistry manipulation. No user interaction is required.

Log Evidence:

https://ia600508.us.archive.org/8/items/cve-2025-24085-24201/cve%202025-24085%3B%2024201.mov

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Exploit Chain

1. Malicious PNG Creation

   • Embedded HEIF payloads with malformed EXIF fields
   • Triggers heap corruption in ATXEncoder (CVE-2025-43300)

2. Silent Trigger via iMessage

   • File auto-processed by MessagesBlastDoorService
   • RCE achieved through WebKit (CVE-2025-24201)

3. Sandbox Escape

   • WebKit bypasses resource isolation to access private assets

4. Privilege Escalation

   • Core Media flaw enables kernel access
   • Exploits mediaplaybackd, codecctl, and IOHIDInterface (CVE-2025-24085)

5. Persistence and Bricking

   • Injects rogue daemons via launchd
   • Hijacks network through wifid
   • Bricks device via IORegistry modification

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Indicators of Compromise

• WebKit resource lookups for internal assets
• Rogue IP assignment: 172.16.101.176
• Modified proxy settings in wifid
• Abnormal access to CloudKeychainProxy
• IORegistry value: IOAccessoryPowerSourceItemBrickLimit = 0

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Timeline

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Disclosure

This exploit chain was discovered being used in the wild and responsibly disclosed to Apple. Patches have since been released. At the time of discovery, active exploitation was confirmed.

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CNVD Certification

This research has been independently verified and certified by the China National Vulnerability Database (CNVD). These official certificates confirm the high-risk status of both vulnerabilities used in the Glass Cage exploit chain:

• CNVD-2025-07885 – Use-After-Free in Apple Media Services

• CNVD-2025-06744 – Buffer Overflow in Apple iOS/iPadOS Core Media

Researcher: Joseph Goydish II Submission Type: Personal Researcher Submission
Certification Authority: CNCERT / CNVD

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Why This Matters

iMessage creates a thumbnail and incoming-text alert as soon as a message is delivered, and that thumbnail is parsed automatically. If that parsing can be weaponized, mere delivery (thumbnail + alert) is enough for instant, silent compromise — no user action, no warning.

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References

• CVE-2025-24085 – Core Media Privilege Escalation
• CVE-2025-24201 – WebKit Remote Code Execution
• CNVD-2025-06744 – iOS/iPadOS Buffer Overflow
• CNVD-2025-07885 – Use-After-Free in Apple Media Services

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