Today, Cisco Talos is disclosing a single out-of-bounds read vulnerability in the Dovecot IMAP server. Dovecot is a popular internet message access protocol, or IMAP, server with performance and security-oriented design. It is a popular choice for robust email servers. In accordance with our coordinated disclosure policy, Talos has worked with Dovecot to ensure that this issue has been resolved. Dovecot has released version 2.2.34 to address this issue. Talos recommends installing this update as quickly as possible on affected systems.
Discovered by Aleksander Nikolic
TALOS-2017-0510 / CVE-2017-14461 is an out-of-bounds read vulnerability in the RFC822 parser implemented in Dovecot IMAP Server 184.108.40.206. RFC822 deals specifically with the standard for ARPA internet text messages. An attacker could use a specially crafted email delivered over SMTP and passed on to Dovecot by the message transfer agent, or MTA, to trigger an out-of-bounds read that potentially results in the disclosure of sensitive information and a denial of service. Full details of the vulnerability are available here.
The following Snort rules will detect exploitation attempts. Note that additional rules may be released at a future date, and current rules are subject to change pending additional vulnerability information. For the most current rule information, please refer to your Firepower Management Center or Snort.org.
Snort Rule: 45248