Threat Encyclopedia

TROJ64_DIDKR.C

Publish date: June 28, 2013

ANALYSIS BY

Rhena Inocencio


PLATFORM:

Windows XP (64-bit), Windows Vista (64-bit), Windows 7 (64-bit)

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

  • Threat Type:Trojan

  • Destructiveness:No

  • Encrypted: Yes

  • In the wild: Yes

OVERVIEW

Infection Channel:

Dropped by other malware


This Trojan may be dropped by other malware.

TECHNICAL DETAILS

File Size:

Varies

File Type:

EXE, DLL

Memory Resident:

Yes

Initial Samples Received Date:

26 Jun 2013

Payload:

Executes files, Connects to URLs/IPs

Arrival Details

This Trojan may be dropped by the following malware:

  • TROJ_DIDKR.C

Installation

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

  • %System%\ole{variable 1}.dll (64-bit) - also detected as TROJ64_DIDKR.C
  • %User Temp%\~DL{number}.tmp (64-bit) - copy of ole{variable 1}.dll (64-bit)

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

Other System Modifications

This Trojan adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{service name of variable 1}Svc\Parameters
ServiceDll = “%System%\ole{variable 1}.dll”

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{service name of variable 1}Svc\Parameters
ServiceMain = “RoutineMain”

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SvcHost
netsvcs = “{default data}, {service name of variable 1}Svc”

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

NOTES:
processed by badette

It enumerates all service names that meet the following condition:

ImagePath = "%SystemRoot%\System32\svchost.exe -k netsvcs"

It then acquires {variable 1} from the filename registered in ServiceDll.

For example:

ImagePath = "%SystemRoot%\System32\svchost.exe -k netsvcs
ServiceDll = "%System%\shsvcs.dll"
{variable 1} = shsvcs

As such, the file ole{variable 1}.DLL is dropped as oleshsvcs.DLL in this example.

The component %System%\ole{variable 1}.dll accesses any of the following sites to receive data:

  • http://webmail.{BLOCKED}shost.com/mail/images/ct.jpg
  • http://www.{BLOCKED}pic.net/pictures/e02947e8573918c1d887e04e2e0b1570.jpg

It saves the received data to %User Temp%\~MR{number}.TMP.

It checks the content of %User Temp%\~MR{number}.tmp if the string BM6W is present.

As of this writing, it checks the present date if equal to or greater than June 25 10:00 AM.

The date to be compared is present in the received data. It is the 4 bytes of data after BM6W.

The component %System%\ole{variable 1}.DLL drops and executes the following file if the conditions above are met:

  • %System%\wuauieop.exe - detected as DDOS_DIDKR.C

SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

10.122.03

FIRST VSAPI PATTERN DATE:

28 Jun 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

Remove the malware/grayware file that dropped/downloaded TROJ64_DIDKR.C

    • TROJ_DIDKR.C

Step 3

Remove the malware/grayware file dropped/downloaded by TROJ64_DIDKR.C

    • DDOS_DIDKR.C

Step 4

Identify and delete files detected as TROJ64_DIDKR.C using either the Startup Disk or Recovery Console

[ Learn More ]

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SvcHost
    • From: netsvcs = “{default data}, {service name of variable 1}Svc”
      To: netsvcs = “{default data}"

Step 6

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\SYSTEM\CurrentControlSet\Services\{service name of variable 1}Svc\Parameters
    • ServiceDll = “%System%\ole{variable 1}.dll”
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\{service name of variable 1}Svc\Parameters
    • ServiceMain = “RoutineMain”

Step 7

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.
  • %User Temp%\~MR{number}.TMP

Step 8

Scan your computer with your Trend Micro product to delete files detected as TROJ64_DIDKR.C. 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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