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BKDR_CYCBOT.DAM

October 12, 2012
 ALIASES:

Backdoor:Win32/Cycbot.G, Backdoor:Win32/Cycbot.G (Microsoft); BackDoor-EXI.gen.s (McAfee); Backdoor.Trojan (Symantec); Trojan.Win32.FakeAV.IS (v) (Sunbelt); Rogue:W32/OpenCloud.A (FSecure)

 PLATFORM:

Windows 2000, XP, 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:

180,224 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

20 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:

  • %User Profile%\Application Data
  • %User Profile%\Application Data\Microsoft
  • %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:\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.)

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
conhost = "%User Profile%\Microsoft\conhost.exe"

Other System Modifications

This backdoor deletes the following folders:

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

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

It adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
SystemCertificates\TrustedPublisher

HKEY_CURRENT_USER\Software\Microsoft\
SystemCertificates\TrustedPublisher\Certificates

HKEY_CURRENT_USER\Software\Microsoft\
SystemCertificates\TrustedPublisher\CRLs

HKEY_CURRENT_USER\Software\Microsoft\
SystemCertificates\TrustedPublisher\CTLs

HKEY_CURRENT_USER\Software\Policies\
Microsoft\SystemCertificates\TrustedPublisher

HKEY_CURRENT_USER\Software\Policies\
Microsoft\SystemCertificates\TrustedPublisher\
Certificates

HKEY_CURRENT_USER\Software\Policies\
Microsoft\SystemCertificates\TrustedPublisher\
CRLs

HKEY_CURRENT_USER\Software\Policies\
Microsoft\SystemCertificates\TrustedPublisher\
CTLs

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "explorer.exe,%User Profile%\Application Data\conhost.exe"

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
Load = "%System%\lvvm.exe"

Dropping Routine

This backdoor drops the following files:

  • %User Profile%\Microsoft\conhost.exe
  • .\
  • %User Temp%\1.exe
  • %User Profile%\Application Data\dwm.exe
  • %User Temp%\2.exe
  • %User Temp%\csrss.exe
  • %User Profile%\MetaData\2BF68F4714092295550497DD56F57004
  • %User Profile%\Content\2BF68F4714092295550497DD56F57004
  • %User Profile%\MetaData\94308059B57B3142E455B38A6EB92015
  • %User Profile%\Content\94308059B57B3142E455B38A6EB92015
  • %User Profile%\MetaData\60E31627FDA0A46932B0E5948949F2A5
  • %User Profile%\Content\60E31627FDA0A46932B0E5948949F2A5
  • %User Profile%\MetaData\0797C381B2F87EB5A1D5573BD15BA4F4
  • %User Profile%\Content\0797C381B2F87EB5A1D5573BD15BA4F4
  • %Temp%\d273.mst
  • %User Profile%\MetaData\7B2238AACCEDC3F1FFE8E7EB5F575EC9
  • %User Profile%\Content\7B2238AACCEDC3F1FFE8E7EB5F575EC9
  • %User Profile%\Application Data\conhost.exe
  • %System%\lvvm.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.. %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.. %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp or C:\WINNT\Temp.. %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\Microsoft\SystemCertificates
    • TrustedPublisher
  • In HKEY_CURRENT_USER\Software\Microsoft\SystemCertificates\TrustedPublisher
    • Certificates
  • In HKEY_CURRENT_USER\Software\Microsoft\SystemCertificates\TrustedPublisher
    • CRLs
  • In HKEY_CURRENT_USER\Software\Microsoft\SystemCertificates\TrustedPublisher
    • CTLs
  • In HKEY_CURRENT_USER\Software\Policies\Microsoft\SystemCertificates
    • TrustedPublisher
  • In HKEY_CURRENT_USER\Software\Policies\Microsoft\SystemCertificates\TrustedPublisher
    • Certificates
  • In HKEY_CURRENT_USER\Software\Policies\Microsoft\SystemCertificates\TrustedPublisher
    • CRLs
  • In HKEY_CURRENT_USER\Software\Policies\Microsoft\SystemCertificates\TrustedPublisher
    • CTLs

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
    • conhost="%User Profile%\Microsoft\conhost.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Winlogon
    • Shell="explorer.exe,%User Profile%\Application Data\conhost.exe"

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_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows
    • Load="%System%\lvvm.exe"

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.
  • %User Profile%\Application Data
  • %User Profile%\Application Data\Microsoft
  • %User Profile%\CryptnetUrlCache\MetaData
  • %User Profile%\Microsoft\CryptnetUrlCache
  • %User Profile%\CryptnetUrlCache\Content

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 Profile%\Microsoft\conhost.exe
  • .\
  • %User Temp%\1.exe
  • %User Profile%\Application Data\dwm.exe
  • %User Temp%\2.exe
  • %User Temp%\csrss.exe
  • %User Profile%\MetaData\2BF68F4714092295550497DD56F57004
  • %User Profile%\Content\2BF68F4714092295550497DD56F57004
  • %User Profile%\MetaData\94308059B57B3142E455B38A6EB92015
  • %User Profile%\Content\94308059B57B3142E455B38A6EB92015
  • %User Profile%\MetaData\60E31627FDA0A46932B0E5948949F2A5
  • %User Profile%\Content\60E31627FDA0A46932B0E5948949F2A5
  • %User Profile%\MetaData\0797C381B2F87EB5A1D5573BD15BA4F4
  • %User Profile%\Content\0797C381B2F87EB5A1D5573BD15BA4F4
  • %Temp%\d273.mst
  • %User Profile%\MetaData\7B2238AACCEDC3F1FFE8E7EB5F575EC9
  • %User Profile%\Content\7B2238AACCEDC3F1FFE8E7EB5F575EC9
  • %User Profile%\Application Data\conhost.exe
  • %System%\lvvm.exe

Step 8

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