Rule: 

--
Sid: 
100000168

-- 
Summary: 
The password-cracking tool Hydra has been detected in HTTP traffic.

--
Impact:
An attacker may be attempting to break into one or more web servers monitored by Snort via a brute-force password attack. If successful, the attacker may gain unauthorized access to internal networks.

--
Detailed Information:
Hydra is a password-cracking tool released by a group of security experts called THC, "The Hacker's Choice." Requests sent by this tool to a web server contain the User-Agent string "Mozilla/4.0 (Hydra)". Since normal browsers' User-Agent strings do not contain the string "(Hydra)", the presence of this string indicates that the Hydra tool is likely being used.

--
Affected Systems:
Any system running a web server.

--
Attack Scenarios:
Attackers will use the Hydra password-cracking tool.

--
Ease of Attack:
Simple, as the program is publicly available and is well-documented.

--
False Positives:
None known.

--
False Negatives:
None known.

--
Corrective Action:
Check system logs and Snort alert logs for suspicious activity, particularly unusual logons. Ensure that secure passwords are being used throughout your network.

--
Contributors:
rmkml
Sourcefire Research Team

--
Additional References

--
