Analysis by: Jimelle Monteser
ALIASES:

TrojanDownloader:Win32/Lerspeng.B (Microsoft), Trojan.Win32.Badur.hvwx (Kaspersky), Trojan.Badur! (Agnitum), Trojan.Win32.Badur.Ar (Baidu-International), TrojanDownloader.Lerspeng.r4 (CAT-QuickHeal), Win32/TrojanDownloader.Small.PSD (ESET-NOD32)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

  TECHNICAL DETAILS

File Size: 90,112 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 13 May 2014

Arrival Details

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CLASSES_ROOT\.max

HKEY_CLASSES_ROOT\.max\ShellNew

HKEY_CLASSES_ROOT\Matrix.Document

HKEY_CLASSES_ROOT\Matrix.Document\DefaultIcon

HKEY_CLASSES_ROOT\Matrix.Document\shell

HKEY_CLASSES_ROOT\Matrix.Document\shell\
open

HKEY_CLASSES_ROOT\Matrix.Document\shell\
open\command

HKEY_CLASSES_ROOT\Matrix.Document\shell\
print

HKEY_CLASSES_ROOT\Matrix.Document\shell\
print\command

HKEY_CLASSES_ROOT\Matrix.Document\shell\
printto

HKEY_CLASSES_ROOT\Matrix.Document\shell\
printto\command

HKEY_CURRENT_USER\Software\Matrix

HKEY_CURRENT_USER\Software\Matrix\
Recent File List

HKEY_CURRENT_USER\Software\Matrix\
Settings

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.max

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.max\ShellNew

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Matrix.Document

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Matrix.Document\DefaultIcon

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Matrix.Document\shell

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Matrix.Document\shell\open

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Matrix.Document\shell\open\
command

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Matrix.Document\shell\print

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Matrix.Document\shell\print\
command

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Matrix.Document\shell\printto

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Matrix.Document\shell\printto\
command

It adds the following registry entries:

HKEY_CLASSES_ROOT\.max
Default = "Matrix.Document"

HKEY_CLASSES_ROOT\.max\ShellNew
NullFile = ""

HKEY_CLASSES_ROOT\Matrix.Document
Default = "Matrix Document"

HKEY_CLASSES_ROOT\Matrix.Document\DefaultIcon
Default = "{malware path}\{malware filename}.exe,0"

HKEY_CLASSES_ROOT\Matrix.Document\shell\
open\command
Default = "{malware path}\{malware filename}.exe"%1""

HKEY_CLASSES_ROOT\Matrix.Document\shell\
print\command
Default = "{malware path}\{malware filename}.exe /p"%1""

HKEY_CLASSES_ROOT\Matrix.Document\shell\
printto\command
Default = "{malware path}\{malware filename}.exe /pt"%1""%2""%3""%4""

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.max
Default = "Matrix.Document"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.max\ShellNew
NullFile = ""

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Matrix.Document
Default = "Matrix Document"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Matrix.Document\DefaultIcon
Default = "{malware path}\{malware filename}.exe,0"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Matrix.Document\shell\open\
command
Default = "{malware path}\{malware filename}.exe"%1""

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Matrix.Document\shell\print\
command
Default = "{malware path}\{malware filename}.exe /p"%1""

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Matrix.Document\shell\printto\
command
Default = "{malware path}\{malware filename}.exe /pt"%1""%2""%3""%4""

Download Routine

This Trojan saves the files it downloads using the following names:

  • %User Temp%\mss{random}.exe

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}oteles.pt/111

  SOLUTION

Minimum Scan Engine: 9.700

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Restart in Safe Mode

[ Learn More ]

Step 3

Delete this registry key

[ 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_CLASSES_ROOT
    • .max
  • In HKEY_CLASSES_ROOT
    • Matrix.Document
  • In HKEY_CURRENT_USER\Software
    • Matrix
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes
    • .max
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes
    • Matrix.Document

Step 4

Search and delete these files

[ Learn More ]
There may be some 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%\mss{random}.exe

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_LERSPENG.A. 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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