BKDR_CYCBOT.BC

 Analysis by: Kathleen Notario

 PLATFORM:

Windows 2000, XP, Server 2003

 OVERALL RISK RATING:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:
 INFORMATION EXPOSURE:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

This backdoor connects to certain URLs. It may do this to remotely inform a malicious user of its installation. It may also do this to download possibly malicious files onto the computer, which puts the computer at a greater risk of infection by other threats. It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size:

Varies

File Type:

PE

Memory Resident:

Yes

Initial Samples Received Date:

11 Nov 2010

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = %Application Data%\Microsoft\Windows\shell.exe

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
svchost = %Application Data%\Microsoft\svchost.exe

It modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
load = %User Temp%\dwm.exe

(Note: The default value data of the said registry entry is {blank}.)

Other System Modifications

This backdoor adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
ProxyServer = http=127.0.0.1:50370

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
ProxyEnable = 1

(Note: The default value data of the said registry entry is 0.)

HKEY_CURRENT_CONFIG\Software\Microsoft\
windows\CurrentVersion\Internet Settings
ProxyEnable = 1

(Note: The default value data of the said registry entry is 0.)

Dropping Routine

This backdoor drops the following files:

  • %Application Data%\Microsoft\stor.cfg - non-malicious file

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

Download Routine

This backdoor connects to the following malicious URLs:

    • http://{BLOCKED}evideochanel.com
    • http://{BLOCKED}onitoringservice.com
    • http://{BLOCKED}udiodevice.com
    • http://{BLOCKED}fectivecasino.com
    • http://{BLOCKED}.com

It saves the files it downloads using the following names:

  • %User Temp%\dwm.exe
  • %Application Data%\Microsoft\svchost.exe
  • %Application Data%\Microsoft\Windows\shell.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.. %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

Other Details

This backdoor does the following:

  • Downloads an updated copy of itself or other malicious files from the said servers by sending HTTP GET request. It does this by appending any of the following strings:
    • /im133.jpg?tq={parameter}
    • /im134.jpg?tq={parameter}
    • /im135.jpg?tq={parameter}

  SOLUTION

Minimum Scan Engine:

8.900

VSAPI PATTERN File:

7.612.01

VSAPI PATTERN Date:

11 Nov 2010

VSAPI PATTERN Date:

11/11/2010 12:00:00 AM

VSAPI OPR PATTERN File:

7.691.00

VSAPI OPR PATTERN Date:

09 Dec 2010

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 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\Winlogon
    • Shell = %Application Data%\Microsoft\Windows\shell.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • svchost = %Application Data%\Microsoft\svchost.exe
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • ProxyServer = http=127.0.0.1:50370

Step 4

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
    • From: load = %User Temp%\dwm.exe
      To: {blank}
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • From: ProxyEnable = 1
      To: 0
  • In HKEY_CURRENT_CONFIG\Software\Microsoft\windows\CurrentVersion\Internet Settings
    • From: ProxyEnable = 1
      To: 0

Step 5

Search and delete this file

[ 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. %Application Data%\Microsoft\stor.cfg

Step 6

Scan your computer with your Trend Micro product to delete files detected as BKDR_CYCBOT.BC. 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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