Cisco IOS XE Software Challenge/Response Bypass Vulnerability

A vulnerability in the request system shell command supported by specific Cisco IOS XE platforms (WS-C3850, WS-C3650, AIR-CT5760, and WS-C4500X) could allow an authenticated, local attacker with administrative privilege (15) to access the underlying Linux root shell.

The vulnerability is due to improper parsing of the challenge response. An attacker could exploit this vulnerability by entering a crafted challenge response. An exploit could allow the attacker to compromise the system. The request system shell command is available only if the service internal command is configured, which is not recommended.

Cisco has confirmed the vulnerability in a security notice; however, software updates are not available.

To exploit this vulnerability, an attacker must authenticate and have local access to the targeted device. These access requirements could reduce the possibility of a successful exploit.

Cisco indicates through the CVSS score that functional exploit code exists; however, the code is not known to be publicly available.