Confidentiality and integrity compromise via zeroed DTLS randomness
Published Apr 3, 2020 · Updated Aug 4, 2024
Insufficient randomness in GnuTLS 3.6.3 through 3.6.12 allows remote attackers to compromise DTLS confidentiality and integrity. The send_client_hello function skips _gnutls_gen_client_random during the initial DTLS ClientHello because an inverted condition treats zero HelloVerifyRequest messages as a reason not to generate random bytes. Exploitation requires network access to the DTLS exchange, and the all-zero 32-byte client random removes the client's entropy contribution from session key establishment.
Summary
What happened
Insufficient randomness in GnuTLS 3.6.3 through 3.6.12 allows remote attackers to compromise DTLS confidentiality and integrity. The send_client_hello function skips _gnutls_gen_client_random during the initial DTLS ClientHello because an inverted condition treats zero HelloVerifyRequest messages as a reason not to generate random bytes. Exploitation requires network access to the DTLS exchange, and the all-zero 32-byte client random removes the client's entropy contribution from session key establishment.
The record
- CVE
- CVE-2020-11501
- Published
- Apr 3, 2020
- Updated
- Aug 4, 2024
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-330
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 3, 2020CVE publishedPublication date reported by the CVE source.
- Aug 4, 2024Record updatedLatest update available in the CVE record.
Exploitability
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