McAfee > Theat Center > Virus Detail Page

Overview

-- Update November 17, 2007 --
The risk assessment of this threat has been updated to Low-Profiled due to media attention at:
http://www.windowsitpro.com/articles/print.cfm?articleid=97582

This is a trojan downloader, it attempts to download and run a program from a remote web site.

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.

Characteristics

-- Update November 17, 2007 --
The risk assessment of this threat has been updated to Low-Profiled due to media attention at:
http://www.windowsitpro.com/articles/print.cfm?articleid=97582

Downloaders are designed to pull files from a remote website and execute the files that have been downloaded.

As it is trivial for the malware author to modify the Downloader to refer to a different website or web address, McAfee write detection routines for Downloaders which as a general rule do not include these strings in the detection routines.

This allows McAfee to write more generic detections for these threats and to proactively protect customers against future minor variants.

Therefore it is not possible to guarantee which website and/or port is being communicated with.

Also, as the website being communicated is normally controlled by the malware author, any files being downloaded can be remotely modified and the behaviour of these new binaries altered - possibly with every user infection.

Upon execution the sample evaluated copies itself to the system and configures
itself to load at system startup.

This trojan attempts to download a Trojan that is detected with current DAT files as BraveSentry.

System Changes

Files Added

• %windir%
\xpupdate.exe

Registry

The following registry keys are created:

• hkey_current_user\software\install

The following registry keys are written:

• hkey_current_user\software\microsoft\windows\currentversion\run

windows update loader:c:\windows\xpupdate.exe

By creating this key the downloader instructs the operating system to execute the downloader every time the user logs on to the computer.

• hkey_current_user\software\install

version:0

This key may be a marker, a key that the downloader uses to determine if it has already been installed or run. Sometimes keys like this can be used to store configuration information or determine if an update is available.

• hkey_current_user\microsoft\windows\currentversion

adp:yzyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy

This key may be a marker, a key that the downloader uses to determine if it has already been installed or run. Sometimes keys like this can be used to store configuration information or determine if an update is available.

Symptoms

Many of these Downloaders install other malware including viruses as well as other Trojans.

Additionally many of them are used to remotely install Adware packages onto the affected host machine for the purposes of gaining referral revenue from the Adware software vendor.

Please note: If Adware is installed via a Downloader it may install it "cleanly" with the relevant uninstaller included for the user to terminate this Adware, although frequently this is not the case.

Method of Infection

N/A. Downloaders are not viruses, and as such do not themselves contain any method to replicate. However they may themselves be downloaded by other viruses and/or Trojans to be installed on the user's system.

Many of these additionally are mass spammed by the author to entice people into double-clicking on them.

Alternatively they may be installed by visiting a malicious web page (either by clicking on a link, or by the website hosting a scripted exploit which installs the Downloader onto the user's system with no user interaction.

Removal

All Windows Users:
Use current engine and DAT files for detection and removal.

Manual Removal Instructions

Delete the registry key(s) as mentioned above
Information on deleting registry keys

Restart the computer

Delete the files mentioned above

Additional Windows ME/XP removal considerations

Variants

Variants

N/A

All Information

Overview -

-- Update November 17, 2007 --
The risk assessment of this threat has been updated to Low-Profiled due to media attention at:
http://www.windowsitpro.com/articles/print.cfm?articleid=97582

This is a trojan downloader, it attempts to download and run a program from a remote web site.

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.

Characteristics

Characteristics -

-- Update November 17, 2007 --
The risk assessment of this threat has been updated to Low-Profiled due to media attention at:
http://www.windowsitpro.com/articles/print.cfm?articleid=97582

Downloaders are designed to pull files from a remote website and execute the files that have been downloaded.

As it is trivial for the malware author to modify the Downloader to refer to a different website or web address, McAfee write detection routines for Downloaders which as a general rule do not include these strings in the detection routines.

This allows McAfee to write more generic detections for these threats and to proactively protect customers against future minor variants.

Therefore it is not possible to guarantee which website and/or port is being communicated with.

Also, as the website being communicated is normally controlled by the malware author, any files being downloaded can be remotely modified and the behaviour of these new binaries altered - possibly with every user infection.

Upon execution the sample evaluated copies itself to the system and configures
itself to load at system startup.

This trojan attempts to download a Trojan that is detected with current DAT files as BraveSentry.

System Changes

Files Added

• %windir%
\xpupdate.exe

Registry

The following registry keys are created:

• hkey_current_user\software\install

The following registry keys are written:

• hkey_current_user\software\microsoft\windows\currentversion\run

windows update loader:c:\windows\xpupdate.exe

By creating this key the downloader instructs the operating system to execute the downloader every time the user logs on to the computer.

• hkey_current_user\software\install

version:0

This key may be a marker, a key that the downloader uses to determine if it has already been installed or run. Sometimes keys like this can be used to store configuration information or determine if an update is available.

• hkey_current_user\microsoft\windows\currentversion

adp:yzyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy

This key may be a marker, a key that the downloader uses to determine if it has already been installed or run. Sometimes keys like this can be used to store configuration information or determine if an update is available.

Symptoms

Symptoms -

Many of these Downloaders install other malware including viruses as well as other Trojans.

Additionally many of them are used to remotely install Adware packages onto the affected host machine for the purposes of gaining referral revenue from the Adware software vendor.

Please note: If Adware is installed via a Downloader it may install it "cleanly" with the relevant uninstaller included for the user to terminate this Adware, although frequently this is not the case.

Method of Infection

Method of Infection -

N/A. Downloaders are not viruses, and as such do not themselves contain any method to replicate. However they may themselves be downloaded by other viruses and/or Trojans to be installed on the user's system.

Many of these additionally are mass spammed by the author to entice people into double-clicking on them.

Alternatively they may be installed by visiting a malicious web page (either by clicking on a link, or by the website hosting a scripted exploit which installs the Downloader onto the user's system with no user interaction.

Removal -

Removal -

All Windows Users:
Use current engine and DAT files for detection and removal.

Manual Removal Instructions

Delete the registry key(s) as mentioned above
Information on deleting registry keys

Restart the computer

Delete the files mentioned above

Additional Windows ME/XP removal considerations

Variants

Variants -

N/A