CVE-2018-15481 UCOPIA Wireless Appliance restricted shell escape (< 5.1.13) feature image

Administrators can connect to their UCOPIA Wireless Appliance using the SSH (TCP/22) or Web SSH (TCP/222) interfaces. The system shell is restricted through the usage of rbash and clish: specific commands or flags are disallowed on purpose, therefore a malicious administrator might want to escape from this shell in order to execute arbitrary commands.

The vulnerability lies in the handling of the ~/.ssh/config file on the UCOPIA system: OpenSSH reads this file when connecting to other machines through SSH. However, a malicious administrator could abuse the LocalCommand instruction to start a sh shell locally after establishing the connection, and therefore obtaining an unrestricted shell.

Exploitation

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External references