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BKDR_BIFROSE.SML

October 12, 2012
 ALIASES:

VirTool:Win32/DelfInject.gen!AC (Microsoft); Backdoor-DZS (McAfee); Backdoor.Trojan (Symantec); Backdoor.Win32.Bifrose.fpg (Kaspersky); Backdoor.Win32.Bifrose.fpg (v) (Sunbelt); Backdoor.Generic.151800 (FSecure)

 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:

711,168 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

28 Nov 2011

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 creates the following folders:

  • %Windows%\InstallDir\
  • %System%\logs

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.. %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

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
HKLM = "%Windows%\InstallDir\dll.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
HKCU = "%Windows%\InstallDir\dll.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{5460C4DF-B266-909E-CB58-E32B79832EB2}
StubPath = "%Windows%\InstallDir\dll.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{5460C4DF-B266-909E-CB58-E32B79832EB2}
StubPath = "%Windows%\InstallDir\dll.exe restart"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{A9260CCB-B2B6-7B3B-D778-C92DBC5AEE18}
StubPath = "%Windows%\log.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{9B71D88C-C598-4935-C5D1-43AA4DB90836}
stubpath = "%System%\logs\log.exe s"

Other System Modifications

This backdoor deletes the following files:

  • %User Profile%\Application Data\--((Mutex))--.cfg
  • %User Profile%\Windows\--((Mutex))--.xtr
  • %System%\logs\log.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.. %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

It adds the following registry keys:

HKEY_CURRENT_USER\SOFTWARE\XtremeRAT

HKEY_CURRENT_USER\SOFTWARE\--((Mutex))--

HKEY_LOCAL_MACHINE\Software\Microsoft\
Active Setup\Installed Components\{5460C4DF-B266-909E-CB58-E32B79832EB2}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{A9260CCB-B2B6-7B3B-D778-C92DBC5AEE18}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\MediaResources\msvideo

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{9B71D88C-C598-4935-C5D1-43AA4DB90836}

HKEY_LOCAL_MACHINE\SOFTWARE\Bifrost

HKEY_CURRENT_USER\SOFTWARE\Bifrost

It adds the following registry entries:

HKEY_CURRENT_USER\Software\XtremeRAT
Mutex = "--((Mutex))--"

HKEY_CURRENT_USER\Software\--((Mutex))--
ServerStarted = "16/11/2011 15:42:13"

HKEY_CURRENT_USER\Software\--((Mutex))--
ServerName = "%Windows%\InstallDir\dll.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Bifrost
nck = {random values}

HKEY_CURRENT_USER\Software\Bifrost
klg = {random values}

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DirectDraw\MostRecentApplication
Name = "svchost.exe"

(Note: The default value data of the said registry entry is mshta.exe.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DirectDraw\MostRecentApplication
ID = 4117ed6

(Note: The default value data of the said registry entry is 41107b3f.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DirectDraw\MostRecentApplication
Name = "calc.exe"

(Note: The default value data of the said registry entry is mshta.exe.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DirectDraw\MostRecentApplication
ID = 3b7d841

(Note: The default value data of the said registry entry is 41107b3f.)

Dropping Routine

This backdoor drops the following files:

  • %User Temp%\Project2.exe
  • %User Temp%\serverxtr.exe
  • %User Temp%\serverslh.exe
  • %User Startup%\serverbif.exe
  • tmp.htm
  • %Windows%\log.exe
  • %Windows%\InstallDir\dll.exe
  • %System%\logs\log.exe

(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.. %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.. %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.. %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.200

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Restart in Safe Mode

[ Learn More ]

Step 3

Delete this registry key

[ 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
    • XtremeRAT
  • In HKEY_CURRENT_USER\SOFTWARE
    • --((Mutex))--
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Active Setup\Installed Components
    • {5460C4DF-B266-909E-CB58-E32B79832EB2}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components
    • {A9260CCB-B2B6-7B3B-D778-C92DBC5AEE18}
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\MediaResources
    • msvideo
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components
    • {9B71D88C-C598-4935-C5D1-43AA4DB90836}
  • In HKEY_LOCAL_MACHINE\SOFTWARE
    • Bifrost
  • In HKEY_CURRENT_USER\SOFTWARE
    • Bifrost

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
    • HKLM="%Windows%\InstallDir\dll.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • HKCU="%Windows%\InstallDir\dll.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{5460C4DF-B266-909E-CB58-E32B79832EB2}
    • StubPath="%Windows%\InstallDir\dll.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{5460C4DF-B266-909E-CB58-E32B79832EB2}
    • StubPath="%Windows%\InstallDir\dll.exe restart"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{A9260CCB-B2B6-7B3B-D778-C92DBC5AEE18}
    • StubPath="%Windows%\log.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{9B71D88C-C598-4935-C5D1-43AA4DB90836}
    • stubpath="%System%\logs\log.exe s"
  • In HKEY_CURRENT_USER\Software\XtremeRAT
    • Mutex="--((Mutex))--"
  • In HKEY_CURRENT_USER\Software\--((Mutex))--
    • ServerStarted="16/11/2011 15:42:13"
  • In HKEY_CURRENT_USER\Software\--((Mutex))--
    • ServerName="%Windows%\InstallDir\dll.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Bifrost
    • nck={random values}
  • In HKEY_CURRENT_USER\Software\Bifrost
    • klg={random values}

Step 5

Restore this modified 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\DirectDraw\MostRecentApplication
    • From: Name="svchost.exe"
      To: Name=mshta.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DirectDraw\MostRecentApplication
    • From: ID=4117ed6
      To: ID=41107b3f
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DirectDraw\MostRecentApplication
    • From: Name="calc.exe"
      To: Name=mshta.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DirectDraw\MostRecentApplication
    • From: ID=3b7d841
      To: ID=41107b3f

Step 6

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.
  • %Windows%\InstallDir\
  • %System%\logs

Step 7

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%\Project2.exe
  • %User Temp%\serverxtr.exe
  • %User Temp%\serverslh.exe
  • %User Startup%\serverbif.exe
  • tmp.htm
  • %Windows%\log.exe
  • %Windows%\InstallDir\dll.exe
  • %System%\logs\log.exe

Step 8

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

Step 9

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %User Profile%\Application Data\--((Mutex))--.cfg
  • %User Profile%\Windows\--((Mutex))--.xtr
  • %System%\logs\log.exe


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