WORM_PALEVO.EF

This worm attempts to connect to certain URLs. Once a connection is established, it waits for commands from the remote user.

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

It uses the default Windows folder icon to trick users into opening the file. Double-clicking the file executes this malware.

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.

However, as of this writing, the said sites are inaccessible.

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%\{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.)

It uses the default Windows folder icon to trick users into opening the file. Double-clicking the file executes this malware.

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

• WQqV+10

It injects codes into the following process(es):

• explorer.exe

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Taskman = %User Profile%\{random name}.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]
shellexecute=ludasambila\\stosamkrila.exe
action=Open folder to see files using Windows Explorer
USEAUTOPLAY=1
open=ludasambila\\stosamkrila.exe
icon=shell32.dll,4
{garbage characters}
shell\\Install\\command=ludasambila\\stosamkrila.exe
shell\\open\\command=ludasambila\\stosamkrila.exe
shell\\explore\\command=ludasambila\\stosamkrila.exe
shell\\open\\command=ludasambila\\stosamkrila.exe

Backdoor Routine

However, as of this writing, the said sites are inaccessible.

Dropping Routine

This worm sets the attributes of its dropped file(s) to the following:

• Hidden
• System
• Read-Only

Other Details

This worm connects to the following possibly malicious URL:

• jebena.{BLOCKED}olic.su
• peer.{BLOCKED}losarske.ru
• teske.{BLOCKED}arke.com
• juice.{BLOCKED}racala.org

NOTES:
Once a connection is established, it waits for commands from the remote user, which may lead to the following actions:

• Download another malicious file
• Hijack search queries