Agent.P

Classification

Rootkit

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W32

Agent.p, W32/Rdriv.A, Troj/Rootkit-X, Trojan.Cachecachekit, Rootkit.Win32.Agent.p

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.

Removal

Automatic action

Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.

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Technical Details

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

Date Created: -

Date Last Modified: -