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TROJ_DLOADER.ALX

October 09, 2012
 Analysis by: Erika Bianca Mendoza
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW


When executed, this malware connects to certain URLs where it downloads another file.

This Trojan may be unknowingly downloaded by a user while visiting malicious websites.

  TECHNICAL DETAILS

File Size:

49,152 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

22 Mar 2011

Payload:

Downloads files

Arrival Details

This Trojan may be unknowingly downloaded by a user while visiting malicious websites.

Other System Modifications

This Trojan adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\PhishingFilter
Enabled = 1

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\PhishingFilter
ShownVerifyBalloon = 3

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Check_Associations = no

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
WarnonZoneCrossing = 0

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
WarnOnPostRedirect = 0

NOTES:

Upon execution, it pauses for five minutes before proceeding with infection.

It then connects to the following URLs where it downloads another file:

  • http://www.news.{BLOCKED}v.com
  • http://software.{BLOCKED}a.com

It appends the following to the above-mentioned URLs:

  • /acheb.aspx?Random={parameter}
  • /bajree.aspx?Random={parameter}
  • /cyacrin.aspx?Random={parameter}
  • /dauber.aspx?Random={parameter}
  • /eaves.aspx?Random={parameter}
  • /kavie.aspx?i5={parameter}
  • /lopper.aspx?i5={parameter}
  • /mabel.aspx?i5={parameter}
  • /noral.aspx?i5={parameter}
  • /opaci.aspx?i5={parameter}
  • /fructi.aspx?e1={parameter}
  • /gynae.aspx?e1={parameter}
  • /hoard.aspx?e1={parameter}
  • /iodal.aspx?e1={parameter}
  • /jiang.aspx?e1={parameter}
  • &g3=yes&h4={parameter}
  • &g3=no&h4={parameter}

where {parameter} is a base64 encoded data that contains the following:

  • browser
  • computer name
  • date and time of installation
  • email clients
  • IP address

The downloaded file is saved as %User Temp%\wmupdate.tmp and executed afterwards. As a result, the malicious routines of the downloaded file are also exhibited on the system. As of this writing, no files are downloaded.

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

7.918.01

FIRST VSAPI PATTERN DATE:

22 Mar 2011

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Identify and terminate files detected as TROJ_DLOADER.ALX

[ Learn More ]
  1. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  2. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

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\Internet Explorer\PhishingFilter
    • Enabled = 1
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\PhishingFilter
    • ShownVerifyBalloon = 3
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • Check_Associations = no
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • WarnonZoneCrossing = 0
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • WarnOnPostRedirect = 0

Step 4

Search and delete these files

[ Learn More ]
There may be some component files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result. %User Temp%\wmupdate.tmp

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_DLOADER.ALX. 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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