Signature validation bypass via prepended zero bytes
Published Jun 22, 2020 · Updated Aug 4, 2024
Improper RSA-PSS signature validation in jsrsasign 3.0.0 through 8.0.16 allows attackers to pass modified signatures as valid. The verifyWithMessageHashPSS function treats signatures with prepended zero bytes as the same BigInteger value instead of rejecting the longer encoding. Only applications invoking RSA-PSS verification are exposed; the demonstrated consequence is acceptance of noncanonical encodings of an otherwise valid signature.
Summary
What happened
Improper RSA-PSS signature validation in jsrsasign 3.0.0 through 8.0.16 allows attackers to pass modified signatures as valid. The verifyWithMessageHashPSS function treats signatures with prepended zero bytes as the same BigInteger value instead of rejecting the longer encoding. Only applications invoking RSA-PSS verification are exposed; the demonstrated consequence is acceptance of noncanonical encodings of an otherwise valid signature.
The record
- CVE
- CVE-2020-14968
- Published
- Jun 22, 2020
- Updated
- Aug 4, 2024
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-119
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 22, 2020CVE publishedPublication date reported by the CVE source.
- Aug 4, 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?
What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
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
- Google Wycheproof RSA-PSS verification proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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