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Historically, a flaw in the SSHv2 implementation of Cisco IOS and IOS XE allowed unauthenticated attackers to bypass user authentication if RSA-based public key authentication was used.
The vulnerability was discovered by researchers at Core Security Technologies, who reported it to Cisco on April 7, 2006. The vulnerability was caused by a buffer overflow in the SSH server's handling of keyboard-interactive authentication. Specifically, the SSH server did not properly validate user input, allowing an attacker to overflow a buffer and execute arbitrary code.
In many instances, "1.25" does not refer to the SSH protocol itself, but rather to a specific software package or a legacy protocol version like . Modern Cisco devices use SSH version 2 (SSHv2) , as SSHv1 is considered insecure due to architectural flaws. cisco ssh 1.25 exploit
| Product Family | IOS Versions Affected | Fixed in Version | | :--- | :--- | :--- | | Cisco 2600, 3600 Series Routers | 12.0(5) - 12.1(5) | 12.1(5)T4 | | Cisco Catalyst 2900/3500 XL Switches | 11.2(8)SA6 - 12.0(5)WC | 12.0(5)WC5 | | Cisco PIX Firewall (SSH feature) | 6.0 - 6.2 | 6.2(2) | | Cisco VPN 3000 Concentrator | 3.0 - 3.5 | 3.5.1 |
The exploit, known as CVE-2006-2371, was a remote code execution vulnerability that could be triggered by an unauthenticated attacker. The exploit involved sending a specially crafted SSH packet to the vulnerable device, which would then execute arbitrary code. The code would be executed in the context of the SSH server, which typically runs with elevated privileges. Historically, a flaw in the SSHv2 implementation of
# Example command to test if the exploit works; in real scenarios, you might not want to execute commands stdin, stdout, stderr = ssh_client.exec_command(f'echo buffer')
The following PoC code demonstrates the exploitation of the Cisco SSH 1.25 vulnerability: Specifically, the SSH server did not properly validate
: Cisco provides a Security Advisory to track which products are affected. SSH Denial of Service (DoS) - CVE-2020-3200
// Create a socket sockfd = socket(AF_INET, SOCK_STREAM, 0); if (sockfd < 0) perror("socket"); exit(1);