Analysis by: Sabrina Lei Sioting

 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

This worm arrives via removable drives. It may be dropped by other malware.

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

It also has rootkit capabilities, which enables it to hide its processes and files from the user.

  TECHNICAL DETAILS

File Size: 135,168 bytes
Memory Resident: Yes
Initial Samples Received Date: 11 Oct 2011

Arrival Details

This worm arrives via removable drives.

It may be dropped by other malware.

Installation

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

  • %User Profile%\Application Data\{random characters}.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
{malware file name} = "%User Profile%\Application Data\{malware file name}.exe"

Propagation

This worm creates the following folders in all removable drives:

  • {drive letter}:\RECYCLER

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

  • {drive letter}:\RECYCLER\{random characters}.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}
shellexecute=RECYCLER\{malware file name}.exe
;{garbage characters}
icon=shell32.dll,7
;{garbage characters}
shell\open\command=RECYCLER\{malware file name}.exe
;{garbage characters}
action=Open folder to view files
;{garbage characters}
shell\explore\command=RECYCLER\{malware file name}.exe
;{garbage characters}
useautoplay=1

Rootkit Capabilities

This worm also has rootkit capabilities, which enables it to hide its processes and files from the user.