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: 335,872 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 21 Aug 2013

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 drops the following copies of itself into the affected system:

  • winlogons.exe
  • c\svchost1.exe
  • d\svchost2.exe
  • e\svchost3.exe
  • f\svchost4.exe
  • g\svchost5.exe
  • h\svchost6.exe
  • wins\svchost.exe

It creates the following folders:

  • c
  • d
  • e
  • f
  • g
  • h
  • wins
  • WinAxA

Autostart Technique

This Trojan modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
shell = "Explorer.exe winlogons.exe"

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

Other System Modifications

This Trojan modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = "2"

(Note: The default value data of the said registry entry is 2.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
HideFileExt = "1"

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

Dropping Routine

This Trojan drops the following files:

  • winlogons.exe
  • c\svchost1.exe
  • d\svchost2.exe
  • e\svchost3.exe
  • f\svchost4.exe
  • g\svchost5.exe
  • h\svchost6.exe
  • wins\svchost.exe
  • %Windows%\c\svchost1.exe
  • %Windows%\d\svchost2.exe
  • %Windows%\e\svchost3.exe
  • %Windows%\f\svchost4.exe
  • %Windows%\g\svchost5.exe
  • %Windows%\h\svchost6.exe
  • All Users.exe
  • Application Data.exe
  • Adobe.exe
  • Acrobat.exe
  • 10.0.exe
  • Replicate.exe
  • Security.exe
  • Setup.exe
  • {AC76BA86-7AD7-1033-7B44-AA0000000001}.exe
  • Microsoft.exe
  • Crypto.exe
  • DSS.exe
  • MachineKeys.exe
  • RSA.exe
  • S-1-5-18.exe
  • HTML Help.exe
  • Media Index.exe
  • Media Player.exe
  • Network.exe
  • Connections.exe
  • Cm.exe
  • Pbk.exe
  • User Account Pictures.exe
  • Default Pictures.exe
  • Desktop.exe
  • Documents.exe
  • My Music.exe
  • My Playlists.exe
  • Sample Music.exe
  • Sample Playlists.exe
  • 0008044E.exe
  • My Pictures.exe
  • Sample Pictures.exe
  • My Videos.exe
  • DRM.exe
  • Favorites.exe
  • Start Menu.exe
  • Programs.exe
  • Accessories.exe
  • Accessibility.exe
  • Communications.exe
  • Entertainment.exe
  • System Tools.exe
  • Administrative Tools.exe
  • Games.exe
  • Startup.exe
  • WinPcap.exe
  • Templates.exe
  • Default User.exe
  • Internet Explorer.exe
  • SystemCertificates.exe
  • My.exe
  • Certificates.exe
  • CRLs.exe
  • CTLs.exe
  • Cookies.exe
  • Local Settings.exe
  • Windows Media.exe
  • 9.0.exe
  • History.exe
  • History.IE5.exe
  • Temp.exe
  • Temporary Internet Files.exe
  • Content.IE5.exe
  • 09RWHJQN.exe
  • BVLBNMKH.exe
  • ZDGZNKA5.exe
  • ZSGKJKO6.exe
  • My Documents.exe
  • NetHood.exe
  • PrintHood.exe
  • Recent.exe
  • SendTo.exe
  • LocalService.exe
  • Credentials.exe
  • S-1-5-19.exe
  • Windows.exe
  • 246FT6TD.exe
  • 9STOYKO4.exe
  • NF72HY20.exe
  • PHOM4UYK.exe
  • NetworkService.exe
  • S-1-5-20.exe
  • Wilbert.exe
  • Identities.exe
  • {8A24C031-62FE-4BF5-94F0-BFD4FBCD674B}.exe
  • S-1-5-21-1645522239-1292428093-682003330-1003.exe
  • Quick Launch.exe
  • MMC.exe
  • Themes.exe
  • Links.exe
  • CD Burning.exe
  • Microsoft .NET Framework 4 Setup_4.0.30319.exe
  • Microsoft Visual C++ 2010 x86 Redistributable Setup_10.0.30319.exe
  • {835818DD-220C-4ABD-946E-0D8660B95E29}.exe

(Note: %Windows% is the Windows folder, which is usually C:\Windows.)

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

Identify and delete files detected as TROJ_MALEX.AA using either the Startup Disk or Recovery Console

[ Learn More ]

Step 3

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: Hidden = "2"
      To: Hidden = ""2""
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: HideFileExt = "1"
      To: HideFileExt = ""1""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: shell = "Explorer.exe winlogons.exe"
      To: shell = ""Explorer.exe""

Step 4

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.
  • winlogons.exe
  • c\svchost1.exe
  • d\svchost2.exe
  • e\svchost3.exe
  • f\svchost4.exe
  • g\svchost5.exe
  • h\svchost6.exe
  • wins\svchost.exe
  • %Windows%\c\svchost1.exe
  • %Windows%\d\svchost2.exe
  • %Windows%\e\svchost3.exe
  • %Windows%\f\svchost4.exe
  • %Windows%\g\svchost5.exe
  • %Windows%\h\svchost6.exe
  • All Users.exe
  • Application Data.exe
  • Adobe.exe
  • Acrobat.exe
  • 10.0.exe
  • Replicate.exe
  • Security.exe
  • Setup.exe
  • {AC76BA86-7AD7-1033-7B44-AA0000000001}.exe
  • Microsoft.exe
  • Crypto.exe
  • DSS.exe
  • MachineKeys.exe
  • RSA.exe
  • S-1-5-18.exe
  • HTML Help.exe
  • Media Index.exe
  • Media Player.exe
  • Network.exe
  • Connections.exe
  • Cm.exe
  • Pbk.exe
  • User Account Pictures.exe
  • Default Pictures.exe
  • Desktop.exe
  • Documents.exe
  • My Music.exe
  • My Playlists.exe
  • Sample Music.exe
  • Sample Playlists.exe
  • 0008044E.exe
  • My Pictures.exe
  • Sample Pictures.exe
  • My Videos.exe
  • DRM.exe
  • Favorites.exe
  • Start Menu.exe
  • Programs.exe
  • Accessories.exe
  • Accessibility.exe
  • Communications.exe
  • Entertainment.exe
  • System Tools.exe
  • Administrative Tools.exe
  • Games.exe
  • Startup.exe
  • WinPcap.exe
  • Templates.exe
  • Default User.exe
  • Internet Explorer.exe
  • SystemCertificates.exe
  • My.exe
  • Certificates.exe
  • CRLs.exe
  • CTLs.exe
  • Cookies.exe
  • Local Settings.exe
  • Windows Media.exe
  • 9.0.exe
  • History.exe
  • History.IE5.exe
  • Temp.exe
  • Temporary Internet Files.exe
  • Content.IE5.exe
  • 09RWHJQN.exe
  • BVLBNMKH.exe
  • ZDGZNKA5.exe
  • ZSGKJKO6.exe
  • My Documents.exe
  • NetHood.exe
  • PrintHood.exe
  • Recent.exe
  • SendTo.exe
  • LocalService.exe
  • Credentials.exe
  • S-1-5-19.exe
  • Windows.exe
  • 246FT6TD.exe
  • 9STOYKO4.exe
  • NF72HY20.exe
  • PHOM4UYK.exe
  • NetworkService.exe
  • S-1-5-20.exe
  • Wilbert.exe
  • Identities.exe
  • {8A24C031-62FE-4BF5-94F0-BFD4FBCD674B}.exe
  • S-1-5-21-1645522239-1292428093-682003330-1003.exe
  • Quick Launch.exe
  • MMC.exe
  • Themes.exe
  • Links.exe
  • CD Burning.exe
  • Microsoft .NET Framework 4 Setup_4.0.30319.exe
  • Microsoft Visual C++ 2010 x86 Redistributable Setup_10.0.30319.exe
  • {835818DD-220C-4ABD-946E-0D8660B95E29}.exe

Step 5

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
  • d
  • e
  • f
  • g
  • h
  • wins
  • WinAxA

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_MALEX.AA. 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.


Did this description help? Tell us how we did.