McAfee Secure sites help keep you safe from identity theft, credit card fraud, spyware, spam, viruses and online scams
Business Home → McAfee Labs → Threat Intelligence

Spam-Skull.dll

This page shows details and results of our analysis on the malware Spam-Skull.dll

Threat Detail

Malware Type: Trojan

Malware Sub-type: Spam

Discovery Date: 2005-12-19

Next Steps:

Overview

This is a trojan detection. Unlike viruses, trojans do not self-replicate. They are spread manually, often under the premise that they are beneficial or wanted. The most common installation methods involve system or security exploitation, and unsuspecting users manually executing unknown programs. Distribution channels include email, malicious or hacked web pages, Internet Relay Chat (IRC), peer-to-peer networks, etc.


Minimum DAT

4653 (2005-12-19)

Updated DAT

4653 (2005-12-19)

 Minimum Engine

5.1.00

File Length

42496 bytes

 Description Added

2005-12-19

Description Modified

2005-12-19

Malware Proliferation

Characteristics

This trojan downloads information from the Internet to construct and send SPAM emails from an infected system. 

Installation

Upon execution of the dropper component (Spam-Skull.dr), the trojan is dropped with the filename msctl32.dll into the %Windir%\System32 folder and injected into the running process WINLOGON.EXE , which ensures the trojan is loaded at system startup.

(Where %Windir% is the Windows directory, for example C:\WINDOWS)

Registry modifications

The following Registry key is created to hook system startup:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify\msctl32.dll

This key contains the following value:

Name: DllName
 Data: C:\WINDOWS\System32\msctl32.dll

SPAM

As previously mentioned this trojan is capable of emailing SPAM from an infected host to a combination of constructed email addresses using the data below.

The trojan downloads text files from one of several sites listed below, each of which contains information for constructing SPAM emails, such as lists of domain names, first names, last names and subject lines.

active.emptyskull.net
price.emptyskull.org

Possible domain names:

Possible names:


Possible subject lines:


Typical email body content:

Symptoms

  • Unexpected SMTP (TCP port 25) traffic from your system.
  • Unexpected network communication with the aforementioned URLs.
  • Existence of the files/Registry keys detailed above.

Method of Infection

Trojans do not self-replicate. They are spread manually, often under the premise that the executable is something beneficial. Distribution channels include IRC, peer-to-peer networks, newsgroup postings, email, etc.

Removal

All Users:

Please use the following instructions for all supported versions of Windows to remove threats and other potential risks:

1.Disable System Restore .

2.Update to current engine and DAT files for detection and removal.

3.Run a complete system scan.

Modifications made to the system Registry and/or INI files for the purposes of hooking system startup, will be successfully removed if cleaning with the recommended engine and DAT combination (or higher).

1. Please go to the Microsoft Recovery Console and restore a clean MBR.

On windows XP:

Insert the Windows XP CD into the CD-ROM drive and restart the computer.
When the "Welcome to Setup" screen appears, press R to start the Recovery Console.
Select the Windows installation that is compromised and provide the administrator password
Issue 'fixmbr' command to restore the Master Boot Record
Follow onscreen instructions
Reset and remove the CD from CD-ROM drive.


On Windows Vista and 7:

Insert the Windows CD into the CD-ROM drive and restart the computer.
Click on "Repair Your Computer"
When the System Recovery Options dialog comes up, choose the Command Prompt.
Issue 'bootrec /fixmbr' command to restore the Master Boot Record
Follow onscreen instructions
Reset and remove the CD from CD-ROM drive.

Variants

United States - English