gnutls -- certificate chain verification DoS

ID 84AB58CF-E4AC-11D8-9B0A-000347A4FA7D
Type freebsd
Reporter FreeBSD
Modified 2004-08-02T00:00:00


Patric Hornik reports on a problem in the certificate chain verification procedures of GnuTLS that may result in a denial-of-service vulnerability:

The certificate chain should be verified from last root certificate to the first certificate. Otherwise a lot of unauthorized CPU processing can be forced to check certificate signatures signed with arbitrary RSA/DSA keys chosen by attacker. In GnuTLS the signatures are checked from first to last certificate, there is no limit on size of keys and no limit on length of certificate chain.