Vigil@nce: Sendmail, truncation of X.509 with null
January 2010 by Vigil@nce
SYNTHESIS OF THE VULNERABILITY
When Sendmail uses certificates, an attacker can send a X.509 certificate with a Subject/Issuer field containing a null character, in order to bypass access restrictions.
Consequences: data reading
Provenance: internet client
Means of attack: no proof of concept, no attack
Ability of attacker: expert (4/4)
Confidence: confirmed by the editor (5/5)
Diffusion of the vulnerable configuration: high (3/3)
Creation date: 31/12/2009
DESCRIPTION OF THE VULNERABILITY
Sendmail can be configured to use X.509 certificates.
However, when a X.509 certificate contains a null character in the Subject/Issuer field, Sendmail truncates this field. This vulnerability is similar to VIGILANCE-VUL-8908 (https://vigilance.fr/tree/1/8908), even if the vulnerable source code is different.
When Sendmail uses certificates, an attacker can therefore send a X.509 certificate with a Subject/Issuer field containing a null character, in order to bypass access restrictions.
Identifiers: BID-37543, VIGILANCE-VUL-9321