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BKDR_ANDROM.ANI

January 20, 2014
 Analysis by: Mark Joseph Manahan
 ALIASES:

Worm:Win32/Gamarue.I (Microsoft), Win32/TrojanDownloader.Wauchos.A trojan (Eset), Backdoor.Trojan (Symantec)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


This backdoor 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:

42,343 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

06 Mar 2013

Arrival Details

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

  • %System Root%\Documents and Settings\All Users\svchost.exe - if running in virtual machine
  • %System Root%\Documents and Settings\All Users\Local Settings\Temp\ms{random characters}.{extension name} - if running in admin account
  • %User Temp%\ms{random characters}.{extension name} - if not running in admin account

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
SunJavaUpdateSched = "%System Root%\Documents and Settings\All Users\svchost.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
{random number} = "%System Root%\Documents and Settings\All Users\Local Settings\Temp\ms{random characters}.{extension name}"

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
Load = "%User Temp%\ms{random}.{extension name}"

Other Details

This backdoor connects to the following URL(s) to check for an Internet connection:

  • www.update.microsoft.com

It connects to the following possibly malicious URL:

  • http://{BLOCKED}e.pl/image.php
  • http://{BLOCKED}nch.ru/image.php
  • http://{BLOCKED}x.pl/image.php
  • http://{BLOCKED}g.pl/image.php
  • http://{BLOCKED}n.ru/image.php

NOTES:
The {extension name} of the dropped copy is any of the following:

  • bat
  • cmd
  • com
  • exe
  • exe
  • pif
  • scr

  SOLUTION

Minimum Scan Engine:

9.300

VSAPI OPR PATTERN File:

9.769.00

VSAPI OPR PATTERN Date:

06 Mar 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

Scan your computer with your Trend Micro product and note files detected as BKDR_ANDROM.ANI

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Delete this 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\CurrentVersion\Run
    • SunJavaUpdateSched = "%System Root%\Documents and Settings\All Users\svchost.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
    • {random number} = "%System Root%\Documents and Settings\All Users\Local Settings\Temp\ms{random characters}.{extension name}"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows
    • Load = "%User Temp%\ms{random}.{extension name}"

Step 5

Search and delete these files

[ Learn More ]
There may be some component 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.
%User Temp%\{random number}.exe
%System Root%\Documents and Settings\All Users\ms{random number}.dat

Step 6

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