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Downloader-ABG

This page shows details and results of our analysis on the malware Downloader-ABG

Threat Detail

Malware Type: Trojan

Malware Sub-type: Downloader

Discovery Date: 2005-05-27

Next Steps:

Overview

This is a trojan detection. Unlike viruses, trojans do not self-replicate. They are spread manually, often under the premise that they are beneficial or wanted. The most common installation methods involve system or security exploitation, and unsuspecting users manually executing unknown programs. Distribution channels include email, malicious or hacked web pages, Internet Relay Chat (IRC), peer-to-peer networks, etc.


Minimum DAT

4501 (2005-05-27)

Updated DAT

4501 (2005-05-27)

 Minimum Engine

5.1.00

File Length

kit: 289792 , downloaders: 1490-1495

 Description Added

2005-05-27

Description Modified

2005-06-06

Malware Proliferation

Characteristics

Detection was added to cover for a malicious 32 bit PE file, originally called "Projet1.exe " , having a filesize of 289792 bytes. The file is internally compressed with the upx packer. 

Basically this is a GUI kit that is a point and click creator of small downloaders.

Upon execution the following GUI is displayed:

The download file is called "wdl.exe " and can vary slightly in size but it is in the 1490-1495 bytes decimal range.

Upon execution it is copied into the %windows or its %system directory as winchost.exe , for example on a win2k test system:

  • c:\WINNT\winchost.exe   (size: 1493 bytes)

To launch itself automaticaly upon systemstart it creates a registry key under:

  • HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run "winchost" , with Data: C:\WINNT\winchost.

Symptoms

  • Presence of the files/filesizes as mentioned above
  • Internet connections to uncommon IP addresses

Method of Infection

  • Manual execution of the binary, there's no exploit associated with the downloader that can be created.

Removal

All Users:
Use current engine and DAT files for detection and removal.

Modifications made to the system Registry and/or INI files for the purposes of hooking system startup, will be successfully removed if cleaning with the recommended engine and DAT combination (or higher).

But in some particular cases, the following steps need to be taken.

Please go to the Microsoft Recovery Console and restore a clean MBR.

On Windows XP:

  • Insert the Windows XP CD into the CD-ROM drive and restart the computer.
  • When the "Welcome to Setup" screen appears, press R to start the Recovery Console.
  • Select the Windows installation that is compromised and provide the administrator password.
  • Issue 'fixmbr' command to restore the Master Boot Record
  • Follow onscreen instructions.
  • Reset and remove the CD from CD-ROM drive.


On Windows Vista and 7:

  • Insert the Windows CD into the CD-ROM drive and restart the computer.
  • Click on "Repair Your Computer".
  • When the System Recovery Options dialog comes up, choose the Command Prompt.
  • Issue 'bootrec /fixmbr' command to restore the Master Boot Record.
  • Follow onscreen instructions.
  • Reset and remove the CD from CD-ROM drive.

Variants

United States - English