BKDR_CYCBOT.UNYG

June 18, 2014
 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:

271,872 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

18 Jun 2014

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:

  • %User Profile%\Application Data\68AD0
  • %Program Files%\LP
  • %Program Files%\LP\6AA6
  • %User Profile%\CryptnetUrlCache\MetaData
  • %User Profile%\Microsoft\CryptnetUrlCache
  • %User Profile%\CryptnetUrlCache\Content

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (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
056.exe = "%Program Files%\LP\6AA6\056.exe"

Other System Modifications

This backdoor deletes the following folders:

  • %User Profile%\My Documents\My Pictures
  • %Start Menu%\Programs\Administrative Tools

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %Start Menu% is the current user's Start Menu folder, which is usually C:\Windows\Start Menu or C:\Documents and Settings\{User name}\Start Menu on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu on Windows Vista and 7.)

It adds the following registry keys:

HKEY_CURRENT_USER\Software\WinRAR

It adds the following registry entries:

HKEY_CURRENT_USER\Software\WinRAR
HWID = "{random values}"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\wscsvc
Start = "3"

(Note: The default value data of the said registry entry is 2.)

Dropping Routine

This backdoor drops the following files:

  • %Program Files%\LP\6AA6\4.tmp
  • %Program Files%\LP\6AA6\056.exe
  • %User Profile%\MetaData\7B2238AACCEDC3F1FFE8E7EB5F575EC9
  • %User Profile%\Content\7B2238AACCEDC3F1FFE8E7EB5F575EC9
  • %User Profile%\MetaData\A44F4E7CB3133FF765C39A53AD8FCFDD
  • %User Profile%\Content\A44F4E7CB3133FF765C39A53AD8FCFDD
  • %User Profile%\MetaData\60E31627FDA0A46932B0E5948949F2A5
  • %User Profile%\Content\60E31627FDA0A46932B0E5948949F2A5
  • %User Profile%\MetaData\0797C381B2F87EB5A1D5573BD15BA4F4
  • %User Profile%\Content\0797C381B2F87EB5A1D5573BD15BA4F4
  • %User Profile%\MetaData\2BF68F4714092295550497DD56F57004
  • %User Profile%\Content\2BF68F4714092295550497DD56F57004
  • %User Profile%\MetaData\94308059B57B3142E455B38A6EB92015
  • %User Profile%\Content\94308059B57B3142E455B38A6EB92015
  • %Temp%\Cab2B.tmp
  • %Temp%\Tar2D.tmp

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp.)

Other Details

This backdoor connects to the following possibly malicious URL:

  • {BLOCKED}5.89.148
  • {BLOCKED}20.96
  • {BLOCKED}85.163
  • {BLOCKED}97.120

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.700

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

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
    • WinRAR

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
    • 056.exe = "%Program Files%\LP\6AA6\056.exe"
  • In HKEY_CURRENT_USER\Software\WinRAR
    • HWID = "{random values}"

Step 5

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\SYSTEM\ControlSet001\Services\wscsvc
    • From: Start = "3"
      To: Start = ""2""

Step 6

Search and delete these components

[ Learn More ]
There may be some components 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.
  • %Program Files%\LP\6AA6\4.tmp
  • %Program Files%\LP\6AA6\056.exe
  • %User Profile%\MetaData\7B2238AACCEDC3F1FFE8E7EB5F575EC9
  • %User Profile%\Content\7B2238AACCEDC3F1FFE8E7EB5F575EC9
  • %User Profile%\MetaData\A44F4E7CB3133FF765C39A53AD8FCFDD
  • %User Profile%\Content\A44F4E7CB3133FF765C39A53AD8FCFDD
  • %User Profile%\MetaData\60E31627FDA0A46932B0E5948949F2A5
  • %User Profile%\Content\60E31627FDA0A46932B0E5948949F2A5
  • %User Profile%\MetaData\0797C381B2F87EB5A1D5573BD15BA4F4
  • %User Profile%\Content\0797C381B2F87EB5A1D5573BD15BA4F4
  • %User Profile%\MetaData\2BF68F4714092295550497DD56F57004
  • %User Profile%\Content\2BF68F4714092295550497DD56F57004
  • %User Profile%\MetaData\94308059B57B3142E455B38A6EB92015
  • %User Profile%\Content\94308059B57B3142E455B38A6EB92015
  • %Temp%\Cab2B.tmp
  • %Temp%\Tar2D.tmp

Step 7

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.
  • %User Profile%\Application Data\68AD0
  • %Program Files%\LP
  • %Program Files%\LP\6AA6
  • %User Profile%\CryptnetUrlCache\MetaData
  • %User Profile%\Microsoft\CryptnetUrlCache
  • %User Profile%\CryptnetUrlCache\Content

Step 8

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