Threat Encyclopedia

PE_RAMNIT.H

Publish date: September 02, 2016

ANALYSIS BY

Roland Marco Dela Paz


PLATFORM:

Windows 2000, XP, Server 2003

OVERALL RISK RATING:
DAMAGE POTENTIAL:
DISTRIBUTION POTENTIAL:
REPORTED INFECTION:

  • Threat Type:File infector

  • Destructiveness:No

  • Encrypted: Yes

  • In the wild: Yes

OVERVIEW


This file infector infects by appending its code to target host files.

TECHNICAL DETAILS

File Size:

Varies

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

10 Aug 2010

Installation

This file infector adds the following mutexes to ensure that only one of its copies runs at any one time:

  • KyUffThOkYwRRtgPP

Autostart Technique

This file infector drops the following files:

  • %Program Files%\Microsoft\DesktopLayer.exe - detected as PE_RAMNIT.H-O
  • %{CurrentDirectory}%\{malware filename}Srv.exe - detected as PE_RAMNIT.H
  • %Program Files%\INTERNET EXPLORER\dmlconf.dat - non-malicious component

(Note: %Program Files% is the Program Files folder, where it usually is C:\Program Files on all Windows operating system versions; C:\Program Files (x86) for 32-bit applications running on Windows 64-bit operating systems.)

It modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = %system%\userinit.exe,,%Program Files%\microsoft\desktoplayer.exe

(Note: The default value data of the said registry entry is %system%\userinit.exe,.)

File Infection

This file infector infects the following file types:

  • dll
  • exe

It infects by appending its code to target host files.

Other Details

Based on analysis of the codes, it has the following capabilities:

  • It opens a hidden instance of iexplore.exe and connects to remote sites to download and execute possible malicious file(s).
  • Injects a malicious VBScript to HTML files.
  • Propagates via removable drives.

SOLUTION

Minimum Scan Engine:

8.900

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Restore this modified registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Userinit=%system%\userinit.exe,,%Program Files%\microsoft\desktoplayer.exe
      To: %system%\userinit.exe

Step 3

Search and delete this file

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
%Program Files%\Internet Explorer\dmlconf.dat
%Program Files%\Microsoft\DesktopLayer.exe

Step 4

Scan your computer with your Trend Micro product to clean files detected as PE_RAMNIT.H. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.


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