Add PoC exploit for CVE-2023-1671

[postmodern]

Add a PoC exploit for CVE-2023-1671, pre-auth command injection vulnerability in the warn-proceed handler of Sophos Web Appliance older than version 4.3.10.4.

Reference PoCs

• https://github.com/ohnonoyesyes/CVE-2023-1671
• https://github.com/W01fh4cker/CVE-2023-1671-POC
• https://github.com/csffs/cve-2023-1671

How to Submit a PoC

See the CONTRIBUTING file for instructions on how to submit a PoC exploit.