Traffic interception via NUL-byte certificate hostname comparison
Published Feb 27, 2020 · Updated Aug 4, 2024
Improper certificate validation in openfortivpn before 1.12.0 with OpenSSL before 1.0.2 allows man-in-the-middle attackers to intercept VPN traffic. In tunnel.c, ssl_verify_cert compares the certificate Common Name with the configured gateway hostname using strncasecmp, which stops at an embedded NUL byte and accepts only the attacker-controlled prefix. Exploitation requires a network interception position and a CA-valid certificate with a crafted Common Name, enabling VPN-server spoofing and disclosure or modification of tunneled traffic.
Summary
What happened
Improper certificate validation in openfortivpn before 1.12.0 with OpenSSL before 1.0.2 allows man-in-the-middle attackers to intercept VPN traffic. In tunnel.c, ssl_verify_cert compares the certificate Common Name with the configured gateway hostname using strncasecmp, which stops at an embedded NUL byte and accepts only the attacker-controlled prefix. Exploitation requires a network interception position and a CA-valid certificate with a crafted Common Name, enabling VPN-server spoofing and disclosure or modification of tunneled traffic.
The record
- CVE
- CVE-2020-7043
- Published
- Feb 27, 2020
- Updated
- Aug 4, 2024
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-295, T1557
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 27, 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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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.
Public exploit references
- Poisoned Common Name certificate generatorproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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