New version of OpenSSL closes security holes in ASN1 parser
Tavis Ormandy from the Google Security Team has notified the OpenSSL developers of a security hole in the current version of their open source library. The errors occur when parsing ASN1 data via the
asn1_d2i_read_bio() function. According to the official OpenSSL advisory and Ormandy's message, the issue affects applications that process external X.509 certificates or public RSA keys. However, the remaining information about the applications that are affected, and the potential consequences, is rather cryptic.
The OpenSSL developers have released versions 1.0.1a, 1.0.0i and 0.9.8v to fix the "ASN1 BIO" problem but the advisories don't state whether the update is urgent. The OpenSSL team talks about a "potentially exploitable vulnerability" and Ormandy provides further details by saying that the issue "can cause memory corruption", but neither say anything about the potential consequences. The full scope of the problem will most likely only be revealed once a Metasploit module is released.
At least the OpenSSH project's own SSH server is unaffected. Damien Miller writes that sshd verifies RSA keys with the custom
openssh_RSA_verify() function which, Miller says, has already helped avoid eight exploitable bugs in the ASN1 parser. Fixed OpenSSL packages for Ubuntu and OpenBSD have already been released. Fixes for Red Hat Enterprise Linux and Fedora are on the way.