Two Vulnerabilities Patched in OpenSSL

The OpenSSL Project announced on Thursday the availability of OpenSSL 1.0.2n, a version that patches two vulnerabilities discovered by a Google researcher.

The flaws were identified by Google’s David Benjamin using the search giant’s OSS-Fuzz fuzzing service.

One of the security holes, CVE-2017-3737, is related to an “error state” mechanism introduced with OpenSSL 1.0.2b. The mechanism is designed to trigger an immediate failure if there is an attempt to continue a handshake after a fatal error has occurred. The problem is that if the SSL_read() or SSL_write() functions are called directly, the mechanism doesn’t work properly.

“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,” OpenSSL said in its advisory.

While this vulnerability could have serious implications, it has only been rated “moderate severity” due to the fact that the targeted application would need to have a bug that causes a call to SSL_read() or SSL_write() after getting a fatal error.

Another vulnerability reported to the OpenSSL Project by Benjamin is CVE-2017-3738, an overflow bug that could allow an attacker to access TLS-protected communications. However, an attack is very difficult to carry out, which is why the issue has been classified as “low severity.”

CVE-2017-3738 is similar to CVE-2017-3736 and CVE-2017-3732, two other vulnerabilities discovered using the OSS-Fuzz tool and patched last month, and CVE-2015-3193, an issue fixed in December 2015.

CVE-2017-3738 affects both the 1.0.2 and 1.1.0 branches of OpenSSL. However, because it’s low severity, OpenSSL 1.1.0 has not been updated on this occasion. The vulnerability will be patched in OpenSSL 1.1.0h when it becomes available.

This is the fourth OpenSSL update from 2017 that patches security bugs and, unless a critical issue is discovered, it will likely be the last. OpenSSL security updates were also announced in January and February.