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

Date	Event
Jan 9, 2025	Exploit chain observed in the wild
Jan 9, 2025	Initial report submitted to US Cert & Apple
Feb 20, 2025	CVE-2025-24085 patched (Core Media)
Mar 7, 2025	CVE-2025-24201 patched (WebKit)
Mar 18, 2025	CNVD-2025-06744 registered
Apr 22, 2025	CNVD-2025-07885 registered

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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

Tactic	Technique
Initial Access	T1203 – Exploitation for Client Exec
Execution	T1059 – Command and Scripting Interp
Persistence	T1547 – Boot or Logon Autostart Exec
Privilege Escalation	T1068 – Exploitation for Priv Esc
Defense Evasion	T1140 – Deobfuscate/Decode Files
Impact	T1499 – Endpoint Denial of Service

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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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