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How the CVE Works:
CVE-2025-24239 is a code-signing downgrade vulnerability in macOS Sequoia (pre-15.4). Attackers exploit improper validation of legacy code signatures, allowing malicious apps to bypass Apple’s strict code-signing requirements. By crafting a malicious binary with an older, weaker signature format, an attacker can execute arbitrary code and access protected user data. The flaw stems from insufficient enforcement of signature version checks during app execution, enabling privilege escalation or data theft.
DailyCVE Form:
Platform: macOS
Version: <15.4
Vulnerability: Code-signing bypass
Severity: Critical
Date: 04/04/2025
What Undercode Say:
Exploit:
- Craft a binary with an older SHA-1 code signature.
- Use `codesign –force –sign -` to apply a fake signature.
3. Bypass Gatekeeper via `spctl –assess –verbose=4`.
Protection:
1. Update to macOS 15.4+.
2. Enable Hardened Runtime: `codesign –options runtime`.
3. Revoke legacy certs via `security delete-certificate`.
Detection:
Check for weak signatures: codesign -dv --verbose=4 /Applications/Suspicious.app Monitor logs: log stream --predicate 'eventMessage CONTAINS "code signature"'
Mitigation Script:
import os
def check_signature(app_path):
os.system(f"codesign --verify --deep --strict {app_path}")
os.system(f"spctl --assess --type exec {app_path}")
Apple’s Patch:
- Enforces SHA-256 signatures.
- Rejects downgraded signature formats.
Threat Intel:
- Exploits observed in wild targeting dev systems.
- CVE chained with sandbox escapes (e.g., CVE-2025-24240).
Forensics:
Extract signatures: codesign --display -r- /path/to/binary Verify TCC access: sqlite3 ~/Library/TCC/TCC.db "SELECT FROM access"
Workaround:
- Disable unsigned app execution:
`sudo spctl –master-enable`
References:
References:
Reported By: https://nvd.nist.gov/vuln/detail/CVE-2025-24239
Extra Source Hub:
Undercode
