Cisco Email Security Appliance Memory Corruption Denial of Service Vulnerability
Severity Rating: High
This vulnerability affects all software versions prior to the first fixed release of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA), both virtual and hardware appliances, if the software is configured for S/MIME Decryption and Verification or S/MIME Public Key Harvesting.
A vulnerability has been identified in Cisco Email Security Appliance and this could be exploited by remote attackers to cause a denial of service condition. The vulnerability resides in the Secure/Multipurpose Internet Mail Extensions (S/MIME) Decryption and Verification or S/MIME Public Key Harvesting features of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) and this could allow an unauthenticated, remote attacker to cause an affected device to corrupt system memory. A successful exploit could cause the filtering process to unexpectedly reload, resulting in a denial of service (DoS) condition on the device.
The vulnerability is caused due to improper input validation of S/MIME-signed emails. An attacker could exploit this vulnerability by sending a malicious S/MIME-signed email through a targeted device. If Decryption and Verification or Public Key Harvesting is configured, the filtering process could crash due to memory corruption and restart, resulting in a DoS condition. The software could then resume processing the same S/MIME-signed email, causing the filtering process to crash and restart again. A successful exploit could allow the attacker to cause a permanent DoS condition. This vulnerability may require manual intervention to recover the ESA.
Users are advised to apply updates.
More information is available on:
Mauritian Computer Emergency Response Team (CERT-MU)
National Computer Board
7th Floor, Stratton Court
La Poudriere Street