➔
search
✕

WORM_KOLAB.YH

October 19, 2012
 Analysis by: Mark Joseph Manahan
 ALIASES:

VirTool:Win32/VBInject.gen!CN (Microsoft), a variant of Win32/Injector.AUR trojan (Eset), Net-Worm.Win32.Kolab (Ikarus)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Propagates via removable drives, Downloaded from the Internet


This worm arrives via removable drives. It may be unknowingly downloaded by a user while visiting malicious websites.

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

It executes commands from a remote malicious user, effectively compromising the affected system.

  TECHNICAL DETAILS

File Size:

221,184 bytes

File Type:

PE

Memory Resident:

Yes

Initial Samples Received Date:

17 Oct 2012

Payload:

Compromises system security, Connects to URLs/IPs

Arrival Details

This worm arrives via removable drives.

It may be unknowingly downloaded by a user while visiting malicious websites.

Installation

This worm drops the following copies of itself into the affected system:

  • %User Profile%\Application Data\Microsoft\svchost.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.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • ddos556mutex

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
svchost.exe = %User Profile%\Application Data\Microsoft\svchost.exe

Propagation

This worm drops copies of itself into all the removable drives connected to an affected system.

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]
shell=verb
open=svchost.exe
action=Open folder to view files
shell\open=Open
icon=%SystemRoot%\system32\SHELL32.dll,4

Backdoor Routine

This worm executes the following commands from a remote malicious user:

  • Steals firefox and sql informations
  • Download arbitrary files
  • Update and uninstall itself
  • Performs ddos attacks (UDP, SSYN)
  • Retrieve system informations

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • {BLOCKED}ent.dyndns.info

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

9.466.05

FIRST VSAPI PATTERN DATE:

17 Oct 2012

VSAPI OPR PATTERN File:

9.467.00

VSAPI OPR PATTERN Date:

18 Oct 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

Identify and terminate files detected as WORM_KOLAB.YH

[ Learn More ]
  1. 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.
  2. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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\CurrentVersion\Run
    • svchost.exe = %User Profile%\Application Data\Microsoft\svchost.exe

Step 4

Search and delete AUTORUN.INF files created by WORM_KOLAB.YH that contain these strings

[ Learn More ]
[autorun]
shell=verb
open=svchost.exe
action=Open folder to view files
shell\open=Open
icon=%SystemRoot%\system32\SHELL32.dll,4

Step 5

Scan your computer with your Trend Micro product to delete files detected as WORM_KOLAB.YH. 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.


Did this description help? Tell us how we did.