Rule: -- Sid: 1557 -- Summary: This event is generated when an attempt is made to exploit a known vulnerability in a CGI web application running on a server. -- Impact: Information gathering and system integrity compromise. Possible unauthorized administrative access to the server or application. Possible execution of arbitrary code of the attackers choosing in some cases. -- Detailed Information: This event is generated when an attempt is made to gain unauthorized access to a CGI application running ona web server. Some applications do not perform stringent checks when validating the credentials of a client host connecting to the services offered on a host server. This can lead to unauthorized access and possibly escalated privileges to that of the administrator. Data stored on the machine can be compromised and trust relationships between the victim server and other hosts can be exploited by the attacker. If stringent input checks are not performed by the CGI application, it may also be possible for an attacker to execute system binaries or malicious code of the attackers choosing. -- Affected Systems: All systems running CGI applications -- Attack Scenarios: An attacker can access an authentication mechanism and supply his/her own credentials to gain access. Alternatively the attacker can exploit weaknesses to gain access as the administrator by supplying input of their choosing to the underlying CGI script. -- Ease of Attack: Simple. Exploits exist. -- False Positives: None known. -- False Negatives: None known. -- Corrective Action: Ensure the system is using an up to date version of the software and has had all vendor supplied patches applied. -- Contributors: Sourcefire Research Team Brian Caswell Nigel Houghton -- Additional References: --