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BKDR_KORLIA.B

March 28, 2013
 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:

20,992 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

05 Feb 2013

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 drops the following file(s)/component(s):

  • %System%\netcat27.dll

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

Other System Modifications

This backdoor adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\6to4

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\6to4\Parameters

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\6to4\Security

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\6to4\Enum

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

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\6to4
Type = "20"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\6to4
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\6to4
ErrorControl = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\6to4
ImagePath = "%SystemRoot%\System32\svchost.exe -k netsvcs"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\6to4
DisplayName = "Network Logon"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\6to4
ObjectName = "LocalSystem"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\6to4\Parameters
ServiceDll = "netcat27.dll"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\6to4\Security
Security = "{Hex Values}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\6to4\Enum
0 = "Root\LEGACY_6TO4\0000"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\6to4\Enum
Count = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\6to4\Enum
NextInstance = "1"

Other Details

This backdoor connects to the following possibly malicious URL:

  • {BLOCKED}.{BLOCKED}.1.179:8080

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

9.710.01

FIRST VSAPI PATTERN DATE:

05 Feb 2013

VSAPI OPR PATTERN File:

9.711.00

VSAPI OPR PATTERN Date:

06 Feb 2013

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

Scan your computer with your Trend Micro product and note files detected as BKDR_KORLIA.B

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

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\SYSTEM\CurrentControlSet\Services
    • 6to4

Step 5

Search and delete these files

[ 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%\netcat27.dll

Step 6

Search and delete the files detected as BKDR_KORLIA.B

*Note: Some component files may be 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.

To stop the malware/grayware from running when certain files are opened:

For Windows 2000, Windows XP, and Windows Server 2003:

  1. Right-click Start then click Search....
  2. In the Named input box, type the name of the file that was detected earlier.
  3. In the Look In drop-down list, select My Computer then press Enter.
  4. Once located, select the file then press SHIFT+DELETE to delete it.

For Windows Vista and Windows 7:

  1. Click Start>Computer.
  2. In the Search Computer input box, type the name of the file detected earlier, and press Enter.
  3. Once located, select the file then press SHIFT+DELETE to delete it.
    *Note: Read the following Microsoft page if these steps do not work on Windows 7.

Step 7

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