BKDR_ANDROM.MA

September 17, 2013
 Analysis by: Anthony Joe Melgarejo
 ALIASES:

Worm:Win32/Gamarue.I (Microsoft), Win32/TrojanDropper.Agent.QID trojan (ESET)

 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: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware

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.

It executes commands from a remote malicious user, effectively compromising the affected system.

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size:

55,81 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

17 Sep 2013

Payload:

Connects to URLs/IPs, Compromises system security, Drops files

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:

  • %All Users Profile%\{random file name}.exe

(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 adds the following processes:

  • svchost.exe
  • msiexec.exe

It injects codes into the following process(es):

  • svchost.exe
  • msiexec.exe

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\policies\
Explorer\Run
{random number} = "%All Users Profile%\{random file name}.exe"

Other System Modifications

This backdoor adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%System%\msiexec.exe = "%System%\msiexec.exe:*:Generic Host Process"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%System%\svchost.exe = "%System%\svchost.exe:*:Generic Host Process"

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • Download and execute arbitrary files
  • Uninstall itself
  • Perform remote shell

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • http://{BLOCKED}lse.com/login.php
  • http://{BLOCKED}o.su/alter.php
  • http://{BLOCKED}c.su/billing.php
  • http://{BLOCKED}es.net/filling.php

Dropping Routine

This backdoor drops the following files:

  • %User Temp%\{random numbers}.exe - TSPY_ZBOT.MA

(Note: %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.)

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

10.284.03

FIRST VSAPI PATTERN DATE:

17 Sep 2013

VSAPI OPR PATTERN File:

10.285.00

VSAPI OPR PATTERN Date:

17 Sep 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

Remove the malware/grayware file dropped/downloaded by BKDR_ANDROM.MA

    • TSPY_ZBOT.MA

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\policies\Explorer\Run
    • {random number} = "%All Users Profile%\{random file name}.exe"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %System%\msiexec.exe = "%System%\msiexec.exe:*:Generic Host Process"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %System%\svchost.exe = "%System%\svchost.exe:*:Generic Host Process"

Step 5

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