Rule: Backdoor.BackOrifice -- Sid: 112, 116 -- Summary: Backdoor.BackOrifice is a Trojan Horse. Server Port: 31337 although in later versions this port can be changed to a value between 1 and 65535 Protocol: UDP although in later versions TCP can also be used -- Impact: Possible theft of data and control of the targeted machine leading to a compromise of all resources the machine is connected to. This Trojan also has the ability to delete data, steal passwords and disable the machine. -- Detailed Information: This Trojan affects the following operating systems: Windows 95 Windows 98 Windows ME Windows NT The Trojan changes system registry settings to add the BackOrifice sever to programs normally started on boot. Due to the nature of this Trojan it is unlikely that the attacker's client IP address has been spoofed. The default name of the server application is UMGR32, which can be changed on first use. The new application may be installed in the system or system32 direcory and the original may also be deleted. Event messages relating to activity from this Trojan are: SID Message --- ------- 112 BackOrifice access (outgoing TCP connection) 116 BackOrifice access (incoming UDP connection) -- Attack Scenarios: This Trojan may be delivered to the target in a number of ways. This event is indicative of an existing infection being activated. Initial compromise can be in the form of a Win32 installation program that may use the extension ".jpg" or ".bmp" when delivered via e-mail for example. -- Ease of Attack: This is Trojan activity, the target machine may already be compromised. Updated virus definition files are essential in detecting this Trojan. -- False Positives: None Known -- False Negatives: None Known -- Corrective Action: Edit the system registry to remove the extra keys or restore a previously known good copy of the registry. Affected registry keys are: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\ HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServices Registry keys added may vary, look for spurious entries in the above locations. BackOrifice may hide the process from viewing inthe Windows task manager. A reboot of the infected machine is recommended. -- Contributors: Original Rule Writer Max Vision <vision@whitehats.com> Sourcefire Research Team Brian Caswell <bmc@sourcefire.com> Nigel Houghton <nigel.houghton@sourcefire.com> -- Additional References: Whitehats arachNIDS http://www.whitehats.com/info/IDS399 Symantec Security Response http://www.symantec.com/avcenter/venc/data/back.orifice2000.trojan.html --
