User impersonation via predictable JWT signing secrets
Published Mar 1, 2021 · Updated Aug 3, 2024
Weak JWT signing-secret generation in YMFE YApi 1.9.2 and earlier allows attackers to forge other users' authentication tokens. The randStr function converts Math.random output to base36 for passsalt, which is reused as the per-user key for signing and verifying JWTs. Exploitation requires three rapidly created accounts and offline signature cracking to recover PRNG state and predict another user's signing key, enabling account impersonation.
Summary
What happened
Weak JWT signing-secret generation in YMFE YApi 1.9.2 and earlier allows attackers to forge other users' authentication tokens. The randStr function converts Math.random output to base36 for passsalt, which is reused as the per-user key for signing and verifying JWTs. Exploitation requires three rapidly created accounts and offline signature cracking to recover PRNG state and predict another user's signing key, enabling account impersonation.
The record
- CVE
- CVE-2021-27884
- Published
- Mar 1, 2021
- Updated
- Aug 3, 2024
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-330, T1606.001
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 1, 2021CVE publishedPublication date reported by the CVE source.
- Aug 3, 2024Record updatedLatest update available in the CVE record.
Exploitability
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What is affected?
Affected products and versions are unavailable in this record.
Attacks
What attackers are doing with it
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Public exploit references
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Technologies
Your stack
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Your stack
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