Software Engineering Institute

CWE-350: Reliance on Reverse DNS Resolution for a Security-Critical Action

Guenter Obiltschnig of Applied Informatics GmbH reports:

The Poco::Net::X509Certificate::verify() method in the POCO C++ Libraries NetSSL library fails to properly validate a wildcard certificate if DNS reverse mapping is broken. In case of a wildcard certificate, the class relies on DNS to obtain aliases for the host name, which are then used for matching against the wildcard domain name(s) in the certificate.

Stable release versions 1.4.6p2 and older are affected, as well as development release version 1.50 to 1.5.2.

After a successful DNS spoofing attack, the attacker may be able to trick a SSL/TLS client into successfully validating a certificate from a malicious server. However, this requires that the certificate first passes the certificate chain validation.

Apply an Update

Vendors and developers which incorporate the POCO C++ NetSSL library into their software should update to version 1.4.6p4 or later.