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WORM_BYBZ.A

March 11, 2011
 Analysis by: Jon Timbre
 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Propagates via removable drives


This worm arrives by connecting affected removable drives to a system.

It adds registry entries to enable its automatic execution at every system startup.

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.

  TECHNICAL DETAILS

File Size:

339,968 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

16 Feb 2010

Arrival Details

This worm arrives by connecting affected removable drives to a system.

Installation

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

  • %User Profile%\Application Data\Microsoft\winlog.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
winlog.exe = %User Profile%\Application Data\Microsoft\winlog.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]
open=winlog.exe
icon=%SystemRoot%\system32\SHELL32.dll,4
action=Open folder to view files
shell\open=Open
shell\open\command=winlog.exe
shell\open\default=1

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

6.852.05

FIRST VSAPI PATTERN DATE:

16 Feb 2010

Step 1

For Windows ME and XP users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

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
    • winlog.exe = %User Profile%\Application Data\Microsoft\winlog.exe

Step 3

Search and delete AUTORUN.INF files created by WORM_BYBZ.A that contain these strings

[ Learn More ]
 [autorun]
open=winlog.exe
icon=%SystemRoot%\system32\SHELL32.dll,4
action=Open folder to view files
shell\open=Open
shell\open\command=winlog.exe
shell\open\default=1

Step 4

Scan your computer with your Trend Micro product to delete files detected as WORM_BYBZ.A 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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