Threat Encyclopedia

BKDR_RBOT.SMB

Publish date: February 10, 2014

ANALYSIS BY

MarfelTi

     MODIFIED BY

     Sabrina Lei Sioting


PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

OVERALL RISK RATING:
DAMAGE POTENTIAL:
DISTRIBUTION POTENTIAL:
REPORTED INFECTION:
INFORMATION EXPOSURE:

  • Threat Type:Backdoor

  • Destructiveness:No

  • Encrypted: No

  • In the wild: Yes

OVERVIEW


This backdoor may be downloaded by other malware/grayware from remote sites.

It deletes the initially executed copy of itself.

TECHNICAL DETAILS

File Size:

172,032 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

18 Aug 2010

Arrival Details

This backdoor may be downloaded by the following malware/grayware from remote sites:

  • WORM_SMALL.ECD

Installation

This backdoor drops the following files:

  • %System%\{random}.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

Autostart Technique

This backdoor registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random}
ImagePath = "%system%\{random}.exe"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random}
DisplayName = "Windows {random}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random}
ObjectName = "LocalSystem"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random}
Description = "Optical sensors monitor the atmosphere to detect the atmosphere of light and adjust the brightness of the display changes"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_{random}\
0000
Service = "{random}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_{random}\
0000
DeviceDesc = "Windows {random}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_{random}\
0000\Control
ActiveService = "{random}"

Other System Modifications

This backdoor adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
ESENT\Process\{random}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_{random}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Eventlog\Application\
Service1

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_{random}\
0000

It adds the following registry entries as part of its installation routine:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
ESENT\Process\{random}\
DEBUG
Trace Level = ""

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Eventlog\Application\
Service1
EventMessageFile = "%WINDOWS%\Microsoft.NET\Framework\v2.0.50727\EventLogMessages.dll"

Other Details

This backdoor connects to the following possibly malicious URL:

  • http://{BLOCKED}t.{BLOCKED}ca.com/it.asp?intTimes=0

It deletes the initially executed copy of itself

SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

7.394.04

FIRST VSAPI PATTERN DATE:

18 Aug 2010

VSAPI OPR PATTERN File:

7.395.00

VSAPI OPR PATTERN Date:

18 Aug 2010

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

Remove the malware/grayware file that dropped/downloaded BKDR_RBOT.SMB

Step 3

Identify and terminate files detected as BKDR_RBOT.SMB

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

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_LOCAL_MACHINE\SOFTWARE\Microsoft\ESENT\Process\
    • {random}
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\Root\
    • LEGACY_{random}
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\
    • {random}
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Eventlog\Application\
    • Service1

Step 6

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.
  • %System%\{random}.exe

Step 7

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