CVE-2025-31200 & CVE-2025-31201 | iMessage Zero‑Click RCE Chain

Summary

This repository documents research into a zero‑click remote exploit chain affecting iOS 18.x. A malformed MP4 audio file delivered via iMessage triggers:

1. Heap corruption in CoreAudio (CVE‑2025‑31200) — in AudioConverterService AAC decoding.
2. Kernel escalation via AppleBCMWLAN/AMPDU handling (CVE‑2025‑31201) — leads to kernel code execution.

In post‑pivot testing, misuse of CryptoTokenKit signing operations was observed, invoking Secure Enclave–backed keys without interactive prompts. Apple patched the vulnerabilities in iOS 18.4.1.

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Verified Behavior

• CVE‑2025‑31200 (CoreAudio) — Heap corruption in AudioConverterService AAC decoder via malformed inMagicCookie. Zero-click, no user interaction required.
• CVE‑2025‑31201 (AppleBCMWLAN) — Kernel privilege escalation following CoreAudio corruption. Fully reproducible on affected devices/builds.
• Zero-click delivery vector — Malicious media processed by iMessage while device is locked.

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Observed Post-Compromise Behavior

• CryptoTokenKit / identityservicesd signing operations invoked from compromised context without UI prompts.
  Important: No Secure Enclave key material was exported; observed misuse is limited to signing operations.
• System instability / PME behavior — Media decode failures correlated with PME enforcement logs, GPU link errors, and mediaplaybackd variant switching, occasionally causing device stalls.

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Scope of Impact

• Affected: iOS ≤ 18.4
• Patched: iOS 18.4.1 (Apr 16, 2025) — fixes CVE‑2025‑31200, CVE‑2025‑31201
• Vector: Zero‑click iMessage/SMS from known sender (bypasses BlastDoor/Blackhole)
• Primary component: AudioConverterService (CoreAudio AAC decoder) — inMagicCookie heap corruption (CVE‑2025‑31200)
• Chained component: AppleBCMWLAN.dext — AMPDU handling → kernel escalation (CVE‑2025‑31201)
• Privileges required: None (initial); kernel achieved post‑chain
• Immediate impact: Unauthorized Secure Enclave–backed signing via CryptoTokenKit (no key exfiltration observed)
• Collateral/system impact: Wireless token manipulation (AWDL/IDS), PME/GPU variant‑switch stalls, launchd SoC stalls
• Impact summary: Integrity (unauthorized signing, token/device impersonation) + Availability (system stalls); Confidentiality — no key export

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Disclosure Timeline

• Reoorted to Apple: Dec 20, 2024
• Re-Reported to Apple & US‑CERT: Jan 21, 2025 (Tracking ID: VRF#25-01-MPVDT)
• Shared with Google Project Zero / Research Team: Apr 11, 2025
• Patched by Apple: Apr 16, 2025 (iOS 18.4.1)
• CVE assignments: CVE‑2025‑31200 and CVE‑2025‑31201

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Impact Statement

An attacker who can trigger this chain remotely can achieve kernel-level compromise and co-opt Secure Enclave–backed signing primitives without exporting key material. This can enable impersonation of device identities and forgery of identity-bound tokens. Severity is high, and runtime hardening and mitigation are recommended.

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Recommendations

• Enforce BlastDoor / attachment inspection for all messages; do not bypass based on sender metadata.
• Apply rigorous input validation for decoder parameters (e.g., inMagicCookie/codec metadata).
• Implement runtime attestation for CryptoTokenKit / Secure Enclave signing operations to verify caller integrity and entitlements.
• Harden wireless driver surfaces and IOKit entrypoints against malformed kernel data.

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License & Disclaimer

Released for defensive research and further study.