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TROJ_STRICTOR.B

April 18, 2014
 ALIASES:

Trojan-PSW.Win32.Deka.ew (Kaspersky); Mal/Agent-AOG (Sophos); Trojan.Win32.Generic.pak!cobra (Sunbelt)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


This Trojan 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:

2,861,848 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

18 Apr 2014

Arrival Details

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

Installation

This Trojan creates the following folders:

  • \?\C:\users\public\Public Document
  • \?\C:\users
  • \?\C:\users\public
  • %User Temp%\Adobe
  • %User Profile%\Msn\Msn2
  • %User Profile%\Msn

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

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
stat = "%User Profile%\Msn2\aagj.bat"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
stat2 = "%User Profile%\Msn2\aagj.bat"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
stat7 = "%System Root%\Users\Public\Public Document\mdej.exe "

Other System Modifications

This Trojan deletes the following files:

  • %System Root%\users\public\Public Document\bare.zip
  • %System Root%\users\public\Public Document\unzip2.exe

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It adds the following registry keys:

HKEY_CURRENT_USER\Software\Adobe\
Adobe Acrobat\10.0

HKEY_CURRENT_USER\Software\Adobe\
Adobe Synchronizer\10.0

HKEY_LOCAL_MACHINE\System\Acrobatbrokerserverdispatchercpp789

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Installer\
Migrated

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile
EnableFirewall = "0"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile
DoNotAllowExceptions = "0"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run\
OptionalComponents\IMAIL
Installed = "1"

(Note: The default value data of the said registry entry is 1.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run\
OptionalComponents\MAPI
Installed = "1"

(Note: The default value data of the said registry entry is 1.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run\
OptionalComponents\MAPI
NoChange = "1"

(Note: The default value data of the said registry entry is 1.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run\
OptionalComponents\MSFS
Installed = "1"

(Note: The default value data of the said registry entry is 1.)

Dropping Routine

This Trojan drops the following files:

  • abc.klm
  • bare.zip
  • crp.exe
  • decj.bat
  • pic.pdf
  • stap.vbs
  • unzip2.exe
  • unzip.exe
  • bar.zip
  • aagj.bat
  • cogj.reg
  • dj.vbs
  • icj.bat
  • iej.bat
  • iewj.bat
  • image.abc
  • images.abc
  • keeprun.ini
  • mdej.abc
  • picture viewer.abc
  • saj.vbs
  • wmsn.klb
  • msn.klc
  • wmsn.klc

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.300

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_CURRENT_USER\Software\Adobe\Adobe Acrobat
    • 10.0
  • In HKEY_CURRENT_USER\Software\Adobe\Adobe Synchronizer
    • 10.0
  • In HKEY_LOCAL_MACHINE\System
    • Acrobatbrokerserverdispatchercpp789
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Installer
    • Migrated

Step 4

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • stat = "%User Profile%\Msn2\aagj.bat"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • stat2 = "%User Profile%\Msn2\aagj.bat"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • stat7 = "%System Root%\Users\Public\Public Document\mdej.exe "
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile
    • EnableFirewall = "0"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile
    • DoNotAllowExceptions = "0"

Step 5

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\OptionalComponents\IMAIL
    • From: Installed = "1"
      To: Installed = ""1""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\OptionalComponents\MAPI
    • From: Installed = "1"
      To: Installed = ""1""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\OptionalComponents\MAPI
    • From: NoChange = "1"
      To: NoChange = ""1""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\OptionalComponents\MSFS
    • From: Installed = "1"
      To: Installed = ""1""

Step 6

Search and delete these components

[ Learn More ]
There may be some components 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.
  • abc.klm
  • bare.zip
  • crp.exe
  • decj.bat
  • pic.pdf
  • stap.vbs
  • unzip2.exe
  • unzip.exe
  • bar.zip
  • aagj.bat
  • cogj.reg
  • dj.vbs
  • icj.bat
  • iej.bat
  • iewj.bat
  • image.abc
  • images.abc
  • keeprun.ini
  • mdej.abc
  • picture viewer.abc
  • saj.vbs
  • wmsn.klb
  • msn.klc
  • wmsn.klc

Step 7

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • \?\C:\users\public\Public Document
  • \?\C:\users
  • \?\C:\users\public
  • %User Temp%\Adobe
  • %User Profile%\Msn\Msn2
  • %User Profile%\Msn

Step 8

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

Step 9

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %System Root%\users\public\Public Document\bare.zip
  • %System Root%\users\public\Public Document\unzip2.exe


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