Signature trust bypass via missing EKU check
Published Aug 9, 2023 · Updated Oct 3, 2024
Signature verification bypass in Trail of Bits uthenticode before 2.0.0 allows attackers to pass unauthorized certificates as valid. SignedData::verify_signature accepts a PE signature after cryptographic verification without checking whether each signer certificate permits code signing in its Extended Key Usage. Exploitation requires a crafted signed PE and causes consumers that trust the library result to accept code signed with an ineligible certificate.
Summary
What happened
Signature verification bypass in Trail of Bits uthenticode before 2.0.0 allows attackers to pass unauthorized certificates as valid. SignedData::verify_signature accepts a PE signature after cryptographic verification without checking whether each signer certificate permits code signing in its Extended Key Usage. Exploitation requires a crafted signed PE and causes consumers that trust the library result to accept code signed with an ineligible certificate.
The record
- CVE
- CVE-2023-40012
- Published
- Aug 9, 2023
- Updated
- Oct 3, 2024
- Vendor
- Trail of Bits
- Product
- uthenticode
- Classifications
- CWE-325, CWE-347, T1553.002
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 9, 2023CVE publishedPublication date reported by the CVE source.
- Oct 3, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 2.0.0
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- A_SSLippery_Slope.exe EKU regression fixtureproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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