Add PoC exploit for CVE-2024-21887

[postmodern]

Add a PoC exploit for CVE-2024-21887, command injection vulnerability in web components of Ivanti Connect Secure (9.x, 22.x) and Ivanti Policy Secure (9.x, 22.x).

Reference PoCs

• https://github.com/zwxxb/CVE-2023-21887/blob/main/3xp.py
• https://github.com/Chocapikk/CVE-2024-21893-to-CVE-2024-21887
• https://github.com/imhunterand/CVE-2024-21887/blob/main/CVE202421887.py

How to Submit a PoC

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