Analysis by: Abraham Latimer Camba

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This worm arrives via removable drives. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

  TECHNICAL DETAILS

File Size: 238,080 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 19 Mar 2012

Arrival Details

This worm arrives via removable drives.

It 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 worm drops the following copies of itself into the affected system and executes them:

  • %User Profile%\Application Data\{random name}.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.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random name} = "%User Profile%\Application Data\{random name}.exe"

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
{random name} = "%User Profile%\Application Data\{random name}.exe"

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
Shell = "explorer.exe,%User Profile%\Application Data\{random name}.exe"

Other System Modifications

This worm adds the following registry keys as part of its installation routine:

HKEY_CURRENT_USER\Software\Microsoft\
Visual Basic

HKEY_CURRENT_USER\Software\Microsoft\
Visual Basic\6.0

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System

Propagation

This worm drops the following copy(ies) of itself in all removable drives:

  • {drive letter}:\Recycler\{random name}.exe

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

The said .INF file contains the following strings:

[autorun]
;{garbage characters}
useautoplay=1
;{garbage characters}
shell\explore\command=RECYCLER\{random name}.exe
;{garbage characters}
action=Open folder to view files
;{garbage characters}
shell\open\command=RECYCLER\{random name}.exe
;{garbage characters}
icon=shell32.dll,7
;{garbage characters}
shellexecute=RECYCLER\{random name}.exe
;{garbage characters}

Other Details

This worm connects to the following URL(s) to get the affected system's IP address:

  • http://api.wipmania.com/

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.834.04
FIRST VSAPI PATTERN DATE: 14 Mar 2012
VSAPI OPR PATTERN File: 8.835.00
VSAPI OPR PATTERN Date: 14 Mar 2012

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

Scan your computer with your Trend Micro product and note files detected as WORM_DORKBOT.JDM

Step 3

Restart in Safe Mode

[ Learn More ]

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {random name} = "%User Profile%\Application Data\{random name}.exe"
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    • {random name} = "%User Profile%\Application Data\{random name}.exe"

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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_CURRENT_USER\Software\Microsoft
    • Visual Basic
  • In HKEY_CURRENT_USER\Software\Microsoft\Visual Basic
    • 6.0
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies
    • System

Step 6

Search and delete the file detected as WORM_DORKBOT.JDM

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files in the search result.

Step 7

Search and delete AUTORUN.INF files created by WORM_DORKBOT.JDM that contain these strings

[ Learn More ]
[autorun]
;{garbage characters}
useautoplay=1
;{garbage characters}
shell\explore\command=RECYCLER\{random name}.exe
;{garbage characters}
action=Open folder to view files
;{garbage characters}
shell\open\command=RECYCLER\{random name}.exe
;{garbage characters}
icon=shell32.dll,7
;{garbage characters}
shellexecute=RECYCLER\{random name}.exe
;{garbage characters}

Step 8

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