How SSH Nuke in Matrix Reloaded works

In the movie Matrix Reloaded, we see Trinity use SSH Nuke to hack a compromised server. This script exploits the SSH CRC-32 vulnerability, specifically known as CVE-2001-0144, which affected older versions of the OpenSSH software. Here’s an explanation of how this vulnerability worked:

Overview of the Vulnerability

The SSH CRC-32 vulnerability exploited a flaw in the handling of CRC (Cyclic Redundancy Check) in the SSH protocol version 1. This vulnerability could allow an attacker to execute arbitrary code on a remote system running an affected SSH daemon (sshd).

Technical Details

1. CRC-32 Integrity Check:

   • The SSH protocol version 1 used a CRC-32 checksum to verify the integrity of data packets.
   • The purpose of CRC-32 was to detect accidental changes to raw data.

2. Vulnerability in CRC-32 Compensation Attack Detector:

   • The vulnerability was found in the CRC-32 compensation attack detector function.
   • This function was supposed to prevent an attacker from tampering with the checksum to produce valid-looking but malicious packets.

3. Exploiting the Buffer Overflow:

   • The flaw allowed for a buffer overflow in the CRC-32 compensation attack detector.
   • An attacker could craft a specially designed SSH packet with an incorrect CRC-32 checksum, which would bypass the integrity check and overflow the buffer.
   • By carefully controlling the data in the overflow, the attacker could overwrite memory and execute arbitrary code on the server.

Steps of the Exploit

1. Sending Malicious Packets:

   • The attacker sends a series of maliciously crafted packets to the SSH server.
   • These packets have incorrect CRC-32 checksums designed to exploit the overflow.

2. Triggering the Overflow:

   • When the SSH server processes these packets, it incorrectly handles the CRC-32 checksums, leading to a buffer overflow.

3. Executing Arbitrary Code:

   • The overflow allows the attacker to inject and execute arbitrary code on the SSH server.
   • This could provide the attacker with unauthorized access to the server, potentially with root privileges.

Mitigation and Resolution

• Patch and Update:

  • The vulnerability was addressed in later versions of OpenSSH.
  • Users were advised to upgrade to the latest version of OpenSSH to mitigate this vulnerability.

• Switch to SSH Protocol Version 2:

  • The vulnerability only affected SSH protocol version 1.
  • Protocol version 2, which is more secure and does not have this flaw, became the recommended version to use.

Conclusion

The SSH CRC-32 vulnerability was a serious security flaw that could allow attackers to gain unauthorized access to systems by exploiting a buffer overflow in the SSH protocol version 1. The exploit involved crafting packets to bypass the integrity checks and trigger an overflow, leading to arbitrary code execution. This vulnerability highlights the importance of using updated and patched software versions and preferring more secure protocols, like SSH version 2.