BKDR_ANDROM.CD

 Analysis by: Jaime Benigno Reyes

 ALIASES:

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

 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:

  • 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:

48,128 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

22 Feb 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:

  • %ProgramData%\svchost.exe (Windows Vista and 7 only)
  • %All User's Profile%\svchost.exe
  • %All User's Temp%\ms{random}.{extension name}

(Note: %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This is usually C:\ProgramData in Windows Vista and 7, or C:\Program Files on Windows 2000, XP (32-bit), and Server 2003, or C:\Program Files (x86) on Windows XP (64-bit).)

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 = "%ProgramData%\svchost.exe" (Windows Vista and 7 only and if Java update is disabled in startup)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
SunJavaUpdateSched = "{All User's Profile}\svchost.exe" (versions other than Windows Vista and 7 and if Java update is disabled in startup)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
{random number} = "%All User's Temp%\ms{random}.{extension name}"

It modifies the following registry entry(ies) to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
SunJavaUpdateSched = "%ProgramData%\svchost.exe" (Windows Vista and 7 only and if Java update is enabled in startup)

(Note: The default value data of the said registry entry is "{Java Installation Folder}\jusched.exe".)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
SunJavaUpdateSched = "{All User's Profile}\svchost.exe" (versions other than Windows Vista and 7 and if Java update is enabled in startup)

(Note: The default value data of the said registry entry is "{Java Installation Folder}\jusched.exe".)

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}\{malware name}.exe = "{malware path}\{malware name}.exe:*:Enabled:Mantle Acne"

NOTES:

The extension name of the dropped copy is any of the following:

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

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

9.746.03

FIRST VSAPI PATTERN DATE:

22 Feb 2013

VSAPI OPR PATTERN File:

9.747.00

VSAPI OPR PATTERN Date:

23 Feb 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.CD

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 = "%ProgramData%\svchost.exe" (Windows Vista and 7 only and if Java update is disabled in startup)
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • SunJavaUpdateSched = "{All User's Profile}\svchost.exe" (versions other than Windows Vista and 7 and if Java update is disabled in startup)

Step 5

Delete the registry entry with an unknown data 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 User's Temp%\ms{random}.{extension name}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • {malware path}\{malware name}.exe = "{malware path}\{malware name}.exe:*:Enabled:Mantle Acne"

Step 6

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • From: SunJavaUpdateSched = "%ProgramData%\svchost.exe" (Windows Vista and 7 only and if Java update is enabled in startup)
      To: SunJavaUpdateSched = "{Java Installation Folder}\jusched.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • From: SunJavaUpdateSched = "{All User's Profile}\svchost.exe" (versions other than Windows Vista and 7 and if Java update is enabled in startup)
      To: SunJavaUpdateSched = "{Java Installation Folder}\jusched.exe"

Step 7

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