CVE-2017-3737

Source
Severity Medium
Remote Yes
Type Information disclosure
Description
OpenSSL 1.0.2 (starting from version 1.0.2b) introduced an "error state" mechanism. The intent was that if a fatal error occurred during a handshake then OpenSSL would move into the error state and would immediately fail if you attempted to continue the handshake. This works as designed for the explicit handshake functions (SSL_do_handshake(), SSL_accept() and SSL_connect()), however due to a bug it does not work correctly if SSL_read() or SSL_write() is called directly. In that scenario, if the handshake fails then a fatal error will be returned in the initial function call. If SSL_read()/SSL_write() is subsequently called by the application for the same SSL object then it will succeed and the data is passed without being decrypted/encrypted directly from the SSL/TLS record layer. In order to exploit this issue an application bug would have to be present that resulted in a call to SSL_read()/SSL_write() being issued after having already received a fatal error.
Group Package Affected Fixed Severity Status Ticket
AVG-550 openssl-1.0 1.0.2.l-2 1.0.2.n-1 Medium Fixed
AVG-549 lib32-openssl 1.1.0.g-1 Medium Not affected
AVG-548 openssl 1.1.0.g-1 Medium Not affected
AVG-480 lib32-openssl-1.0 1.0.2.l-2 1.0.2.n-1 Medium Fixed
Date Advisory Group Package Severity Description
17 Dec 2017 ASA-201712-11 AVG-480 lib32-openssl-1.0 Medium multiple issues
References
https://www.openssl.org/news/vulnerabilities.html#2017-3737
https://www.openssl.org/news/secadv/20171207.txt
https://github.com/openssl/openssl/commit/898fb884b706aaeb283de4812340bb0bde8476dc
Notes
Only affects version 1.0.2