Cisco Expressway Series and Cisco TelePresence Video Communication Server Vulnerabilities

Vulnerability

Multiple vulnerabilities exist in the API and in the web-based management interface of Cisco Expressway Series (Expressway-C and Expressway-E) and Cisco TelePresence Video Communication Server (VCS). These flaws could allow a remote attacker to overwrite arbitrary files or conduct null byte poisoning attacks on an affected device. Affected versions include those prior to the fixed releases detailed in Cisco Security Advisory cisco-sa-expressway-overwrite-3buqW8LH [1].

Exploitation

An attacker must have network access to the affected device's API or web-based management interface. No authentication is required for exploitation. The attacker sends crafted requests to overwrite arbitrary files or inject null bytes, exploiting insufficient input validation [1].

Impact

Successful exploitation allows an attacker to overwrite arbitrary files on the device or perform null byte poisoning, potentially leading to denial of service, data corruption, or further compromise of the system. The attacker gains the ability to modify critical system files without proper authorization [1].

Mitigation

Cisco has released free software updates to address these vulnerabilities. Customers with service contracts should obtain fixes through their usual update channels. For customers without service contracts, Cisco recommends contacting the Cisco Technical Assistance Center (TAC) to obtain the fixed software. No workarounds are available [1].