Analysis by: Jimelle Monteser
ALIASES:

Trojan-Downloader.Win32.Andromeda.adxa (Kaspersky), Win32/TrojanDownloader.Wauchos.L trojan (NOD32), Troj/Mdrop-FIL (Sophos Lite)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

  TECHNICAL DETAILS

File Size: 59,904 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 27 Aug 2013

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This Trojan drops the following copies of itself into the affected system:

  • %All Users Profile%\Local Settings\Temp\ms{random}.{random extension name}

(Note: %All Users Profile% is the All Users or Common profile folder, which is C:\Documents and Settings\All Users in Windows 2000, XP, and Server 2003, and C:\ProgramData in Windows Vista and 7.)

It creates the following folders:

  • %All Users Profile%\Local Settings\Temp

(Note: %All Users Profile% is the All Users or Common profile folder, which is C:\Documents and Settings\All Users in Windows 2000, XP, and Server 2003, and C:\ProgramData in Windows Vista and 7.)

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
{random number} = "%All Users Profile%\Local Settings\Temp\ms{random}.{random extension name}"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\policies\
Explorer

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}9.ru

NOTES:

The extension name of its dropped copy may be any of the following:

  • BAT
  • CMD
  • COM
  • EXE
  • PIF
  • SCR

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 10.246.03
FIRST VSAPI PATTERN DATE: 29 Aug 2013
VSAPI OPR PATTERN File: 10.247.00
VSAPI OPR PATTERN Date: 30 Aug 2013

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

Restart in Safe Mode

[ Learn More ]

Step 3

Delete this registry key

[ 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\CurrentVersion\policies
    • Explorer

Step 4

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %All Users Profile%\Local Settings\Temp

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_ANDROMED.GC. 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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