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BKDR_ANDROM.EC

September 07, 2013
 Analysis by: Anthony Joe Melgarejo
 ALIASES:

Worm:Win32/Gamarue.I (Microsoft), Backdoor.Win32.Androm (Ikarus)

 PLATFORM:

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

 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:

50,176 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

14 May 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:

  • %All Users Profile%\Local Settings\Temp\ms{random characters}.{file extension}
  • %All Users Profile%\svchost.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.)

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 = "%All Users Profile%\svchost.exe"

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

Other System Modifications

This backdoor creates the following registry entry(ies) to bypass Windows Firewall:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
{malware path and file name} = "{malware path and file name} "{malware path and file name}:*:Enabled:{File Description}""

Other Details

This backdoor connects to the following possibly malicious URL:

  • http://{BLOCKED}asen.ru/images/Core.dll.pack
  • http://{BLOCKED}asen.ru/images/image.php

NOTES:

Where {file extension} is any of the following:

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

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

9.918.05

FIRST VSAPI PATTERN DATE:

14 May 2013

VSAPI OPR PATTERN File:

9.919.00

VSAPI OPR PATTERN Date:

14 May 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.EC

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 = "%All Users Profile%\svchost.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
    • {random number} = "%All Users Profile%\Local Settings\Temp\ms{random characters}.{file extension}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • {malware path and file name} = "{malware path and file name}:*:Enabled:{File Description}"

Step 5

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