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

CVE-2025-24201 – WebKit Remote Code Execution
CVE-2025-24085 – Core Media Privilege Escalation

Reported to Apple: January 9, 2025
Patched: February–March 2025
Tested On: iPhone 14 Pro Max (iOS 18.2.1)
CVSS Base Score: 9.8 (Critical)

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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. 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.

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Exploit Chain

1. Malicious PNG Creation

   • Embedded HEIF payloads with malformed EXIF fields
   • Triggers heap corruption in ATXEncoder

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

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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MITRE ATT&CK Mapping

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Legal Notice

This repository is provided for research and educational purposes only.
The techniques described must not be used against systems without proper authorization.
The author assumes no liability for misuse or damage resulting from the information contained herein.

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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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