Cisco IOS Penetration Testing with Metasploit

While the individual modules and supporting libraries were added to the open source framework, the commercial products can now chain these modules together to quickly compromise all vulnerable devices on the network. The screen shot below gives you an idea of what a successful penetration test can look like:

o begin with, I should state that a properly configured Cisco device is a tough target to crack. Vulnerabilities exist in IOS, just like any other piece of software, but only a few folks have managed to leverage memory corruption flaws into code execution. For this reason, the majority of real-world attacks against IOS devices tend to focus on two areas: poor configuration and weak passwords.

Before we dive into the specifics, lets review the current “state of the art” in Cisco IOS security testing. Vulnerability scanners do a great job of identifying out of date IOS installations by comparing version strings. This works well for determining whether a device is patched, but doesn’t help a penetration tester who doesn’t have a deep background in IOS exploitation. With few exceptions, this leaves a small number of services that are commonly exposed in production environments. These services include SNMP, Telnet, SSH, and HTTP. You may also find Finger running or relay services for media protocols like SIP and H.323. For remote access, the first four are what most of us have to work with, and even then, its rare to find a properly configured router with any of those services exposed to the network at large.

The Cisco IOS HTTP service has a few well-known vulnerabilities on older versions of the operating system. The two we care about as penetration testers both relate to authentication bypass. The first flaw, CVE-2000-0945, relates to missing authentication in the IOS Device Manager interface. This vulnerability allows unauthenticated, often privileged access to the IOS installation through the web interface. The second vulnerability, CVE-02001-0537, allows an attacker to bypass authentication by specifying an authentication level higher than “15″ in the request to the HTTP service. This also provides privileged access to the device through the web interface. The open source Metasploit Framework now provides two modules for exploiting these vulnerabilities:

1. /auxiliary/scanner/http/cisco_device_manager
2. /auxiliary/scanner/http/cisco_ios_auth_bypass

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NJ Ouchn

"Passion is needed for any great work, and for the revolution, passion and audacity are required in big doses"