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BKDR_SINOWAL.COO

November 06, 2013
 Analysis by: Sabrina Lei Sioting
 ALIASES:

W32/Sinowal.TMB!tr.bdr (Fortinet), Backdoor.Win32.Sinowal (Ikarus), Backdoor.Win32.Sinowal.tmb (Kaspersky), Win32/TrojanDownloader.Mebload.AW 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:

  • 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 runs certain commands that it receives remotely from a malicious user. Doing this puts the affected computer and information found on the computer at greater risk.

It gathers certain information on the affected computer.

  TECHNICAL DETAILS

File Size:

242,688 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

05 Nov 2013

Payload:

Compromises system security

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 files:

  • %All User Profile%\Application Data\{random}\{random}.dat
  • %All User Profile%\Application Data\{random}\{random}.dll
  • %All User Profile%\Application Data\{random}\{name}.dat - configuration file
  • %All User Profile%\Application Data\{random}\{name}.dll - also deteced as BKDR_SINOWAL.COO

It creates the following folders:

  • %All User Profile%\Application Data\{random}

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • XUOBRFUMLPRFEXEXMLHXT

Autostart Technique

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

HKEY_CLASSES_ROOT\CLSID\{CLSID}\
InprocServer32
{default} = "%All User Profile%\Application Data\{random}\{name}.dll"

HKEY_CURRENT_USER\Software\Classes\
CLSID\{CLSID}\InprocServer32
{default} = "%All User Profile%\Application Data\{random}\{name}.dll"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\ShellServiceObjectDelayLoad
{value} = "{CLSID}"

Backdoor Routine

This backdoor executes the following command(s) from a remote malicious user:

  • Download other files

As of this writing, the said servers are currently inaccessible.

Information Theft

This backdoor gathers the following information on the affected computer:

  • All running processes
  • Installed software that are registered in the HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall key

Stolen Information

This backdoor sends the gathered information via HTTP POST to the following URL:

  • http://{BLOCKED}tiousannotating.in/search2?fr=altavista&itag=ody&q={parameter}&kgs=1&kls=0
  • http://{BLOCKED}.228.251/search2?fr=altavista&itag=ody&q={parameter}&kgs=1&kls=0

Other Details

This backdoor displays the following message boxes:

when the process avgui.exe is running:


NOTES:

It executes the .dll that it drops using the following command:

  • %System%\cmd.exe /c %System%\regsvr32.exe /s %All User Profile%\Application Data\{random}\{name}.dll

As a result, malicious routines of the dropped .dll are exhibited on the affected system.

Where {name} in .dat could be any of the following:

  • bass
  • ccdxmmde
  • colu
  • dfdd
  • drss
  • dsdd
  • du44
  • dumd
  • elct
  • ffxd
  • i3u4
  • ii33
  • jdlr
  • kdkd
  • msxx
  • ned9
  • nudr
  • qnud
  • rexx
  • rrxx
  • ssde
  • uloc
  • vvve
  • werr
  • wjdj
  • xdor
  • xes2
  • xessmsxe

where {name} in .dll could be any of the following:

  • mswd
  • mscc
  • msdr
  • msdd
  • msee
  • wsse
  • msseedir
  • lmbd
  • mmdd

where {CLSID} could be any of the following:

  • {118BEDCC-A901-4203-B4F2-ADCB957D1887}
  • {312BED3C-A901-4203-B4F2-ADCB957D1887}
  • {F12BE2CC-A901-4203-B4F2-ADCB957D1887}
  • {312BFDCE-A901-4203-B4F2-ADCB957D1887}
  • {212B3DCC-A901-4203-B4F2-ADCB957D1887}
  • {A12BEDCC-A901-4203-B4F2-ADCB957D1887}

where {value} could be any of the following:

  • Copier
  • WindowsCopy
  • MicrosoftCopy
  • MSCopy
  • CopierMircosoft
  • MSCPY

  SOLUTION

Minimum Scan Engine:

9.300

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

Identify and delete files detected as BKDR_SINOWAL.COO using the Recovery Console

[ Learn More ]

Step 3

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_CURRENT_USER\Software\Classes\CLSID\{CLSID}\InprocServer32
    • {default} = "%All User Profile%\Application Data\{random}\{name}.dll"
  • In HKEY_CLASSES_ROOT\CLSID\{CLSID}\InprocServer32
    • {default} = "%All User Profile%\Application Data\{random}\{name}.dll"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\ShellServiceObjectDelayLoad
    • {value} = "{CLSID}"

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 User Profile%\Application Data\{random}

Step 5

Search and delete this file

[ Learn More ]
There may be some 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.
%All User Profile%\Application Data\{random}\{random}.dat
%All User Profile%\Application Data\{random}\{random}.dll
%All User Profile%\Application Data\{random}\{name}.dat
%All User Profile%\Application Data\{random}\{name}.dll

Step 6

Scan your computer with your Trend Micro product to delete files detected as BKDR_SINOWAL.COO. 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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