619555798/cve-2023-42824

GitHubRepository PoCExploit

PoC files

16 files

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GitHub
Analysisdeepseek-v4-pro:cloud ·

Technical assessment

A multi-threaded C program that exploits a copy-on-write (COW) bypass vulnerability (CVE-2023-42824) in the XNU kernel's virtual memory subsystem. It uses Mach out-of-line (OOL) memory messages and concurrent page faults to trigger a race condition, allowing a writer thread's modifications to become visible through a supposedly COW-mapped copy, demonstrating privilege escalation capability.

Backdoor review

No backdoor observed in reviewed code

The supplied evidence consists of a README and two C source files implementing a proof-of-concept for CVE-2023-42824, a local privilege escalation via a copy-on-write bypass. The code performs memory mapping, remapping, and race-condition exploitation using Mach APIs, which is consistent with the stated vulnerability. No backdoor, deceptive payload, or concealed operator-directed harm is observed. The code does not establish persistence, exfiltrate data, or execute unrelated commands.

ClassificationExploit
Model confidence95%
AuthenticationNot required
LanguagesC
Target softwareXNU kernel (iOS/macOS)
Attack typesrace conditionprivilege escalation
Evidence & reasoningClassification basis · observed behavior · safety review
Technical evidence

Classification basis and observed behavior

Classification basis

The code actively exercises a race condition to achieve a COW bypass, which is the vulnerability itself. It does not merely check for the vulnerability; it performs the write, detects the bypass, and logs success. This is exploit behavior, not a scanner.

mdc2/vm_fault_poc.c:460-528

Requirements

  • Local code execution on a vulnerable XNU kernel version (iOS before 16.7.1 or 17.0.3).mdc2/vm_fault_poc.c:1

Observed behavior

  • Creates a shared memory mapping and a remapped copy via mach_vm_remap, then spawns writer, copy-churn, and fault-contention threads to race writes against OOL message sends. Detects when a writer's value appears in the OOL copy, confirming a COW bypass, and logs the event.mdc2/vm_fault_poc.c:246-543
  • Uses mach_vm_protect to flip page protections and induce faults, increasing race window.mdc2/vm_fault_poc.c:339-369
  • Logs successful COW bypass with page number and confirmation method.mdc2/vm_fault_poc.c:520-522
Safety-review evidence

Behaviors behind the backdoor verdict

Observables

Vulnerability Exploit
CVE-2023-42824The code implements a race condition to bypass copy-on-write protections, matching the described local privilege escalation vulnerability.mdc2/vm_fault_poc.c:1-819
Mach Api Usage
mach_vm_remap, mach_vm_protect, mach_vm_deallocateThe PoC uses Mach VM APIs to manipulate memory mappings and trigger the vulnerability, which is expected for an iOS/macOS kernel exploit.mdc2/vm_fault_poc.c:19-26mdc2/vm_fault_poc.c:413-418
Review boundaries

What the analysis did not establish

  • One binary file (UserInterfaceState.xcuserstate) was not analyzed; it is unlikely to affect classification.
  • Only 3 of 15 text files were included; the remaining 12 files are omitted, but the included files contain the core exploit logic.
  • One binary file (UserInterfaceState.xcuserstate) was flagged but not analyzed; it is a standard Xcode user state file and unlikely to contain executable payloads.
  • Only 3 of 16 total files were provided as text; the remaining 12 text files were omitted due to size constraints, but the core exploit logic is fully represented.
Model interpretation

This review is limited to the supplied PoC code and context. It does not assert that the code works or is safe to execute.

Linked vulnerabilities

1