F-Secure Rootkit Information Pages : Agent.p [Summary] | [Disinfection] | [Detailed Description] Name: Agent.p Alias: W32/Rdriv.A, Troj/Rootkit-X, Trojan.Cachecachekit, Rootkit.Win32.Agent.p Category: Rootkit Platform: Win32 Summary Agent.p is a kernel-mode rootkit driver that hides processes in addition to inbound and outbound TCP connections. It has been utilized by various Sdbot and Rbot variants to hide their presence on the compromised system. Disinfection Detection and Disinfection of Rootkits If the rootkit is not detected or it is hidden so that FSAV cannot detect its file, it is still possible to detect the malicious activity by scanning the system with a generic rootkit scanner such as F-Secure BlackLight. More information about F-Secure BlackLight Rootkit Elimination Technology can be found here: http://www.f-secure.com/blacklight/ The BlackLight utility is also able to disinfect computers that are infected by rootkits. Back to the Top Detailed Description Agent.p is a combination of two well known open source rootkit drivers: fu and JiurlPortHide. It is often dropped and controlled by a user-mode malware component. The user-mode component instructs the driver to hide its process, inbound and outbound TCP connections it has opened, and the driver module itself. Installation Agent.p is installed by the user-mode malware component utilizing it. The user-mode component drops, installs and loads the driver. This results in one registry key: HKLM\SYSTEM\CurrentControlSet\Services\[driver_name] where [driver_name] represents the name of the driver file without the .sys extension. Often the driver has been named as "rdriv.sys". Hiding Technique Agent.p is able to hide the following items: Processes Kernel-mode modules Inbound and outbound TCP connections Process and kernel-mode module hiding is based on fu (see fu description) source code. TCP connection hiding is based on the source code of JiurlPortHide with minor modifications. To hide TCP connections, Agent.p replaces the function pointer for the NtDeviceIoControlFile from the kernel's System Service Table with its own hook function. The hook function filters IOCTL_TCP_QUERY_INFORMATION_EX requests to the TCP/IP driver and removes any entry where source or destination port are any of the following: 445 139 135 1433 4367 Back to the Top Write-up: Kimmo Kasslin Technical Details: Kimmo Kasslin, March 14, 2006 Description Updated: Sean Sullivan, March 14, 2006 F-Secure Corporation