CVE-2017-3737

Priority
Medium
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. OpenSSL version 1.0.2b-1.0.2m are affected.
Fixed in OpenSSL 1.0.2n. OpenSSL 1.1.0 is not affected.
References
Notes
 leosilva> this issue does not affect OpenSSL 1.1.0
 mdeslaur> 1.0.2b introduced a security hardening mechanism designed to
 mdeslaur> protect against bugs in application code.
 mdeslaur> https://git.openssl.org/?p=openssl.git;a=commit;h=e4f77bf1833245d2b6aa4ce6a16c85e1cdf78589
 mdeslaur> This CVE applies to the hardening mechanism being incomplete.
 mdeslaur> openssl versions older than 1.0.2b don't have the hardening
 mdeslaur> mechanism at all.
Assigned-to
mdeslaur
Package
Upstream:needs-triage
Ubuntu 12.04 ESM (Precise Pangolin):not-affected (code not present)
Ubuntu 14.04 LTS (Trusty Tahr):not-affected (code not present)
Ubuntu 16.04 LTS (Xenial Xerus):released (1.0.2g-1ubuntu4.10)
Ubuntu 17.04 (Zesty Zapus):released (1.0.2g-1ubuntu11.4)
Ubuntu 17.10 (Artful Aardvark):released (1.0.2g-1ubuntu13.3)
Ubuntu 18.04 LTS (Bionic Beaver):pending (1.0.2g-1ubuntu15)
Patches:
Upstream:https://git.openssl.org/?p=openssl.git;a=commit;h=898fb884b706aaeb283de4812340bb0bde8476dc
Upstream:https://git.openssl.org/?p=openssl.git;a=commit;h=c7383fb5f21aa3451f76bb98bdd5a96b070a2c47 (test)
More Information

Updated: 2017-12-15 20:20:12 UTC (commit 13913)