TROJ_MALEX.AE

October 09, 2012
 Analysis by: Rhena Inocencio
 ALIASES:

Trojan:Win32/Malex.gen!F (Microsoft), Trojan.Win32.Swisyn.cacm (Kaspersky)

 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.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

16,442,880 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

01 Aug 2012

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:

  • %Program Files%\smss.exe

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files.)

Autostart Technique

This Trojan registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\ﾏｵﾍｳｹﾘｼ・ﾎ
ImagePath = "%Program Files%\smss.exe"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\ﾏｵﾍｳｹﾘｼ・ﾎ
Type = "10"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\ﾏｵﾍｳｹﾘｼ・ﾎ
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\ﾏｵﾍｳｹﾘｼ・ﾎ
ErrorControl = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\ﾏｵﾍｳｹﾘｼ・ﾎ
DisplayName = "System Service"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\ﾏｵﾍｳｹﾘｼ・ﾎ
ObjectName = "LocalSystem"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\ﾏｵﾍｳｹﾘｼ・ﾎ

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_*00CF*00B5*00CD*00B3*00B9*00D8*00BC*00FC*00B7*00FE*00CE*00F1

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}7.{BLOCKED}3.in:8456/z/arp.exe
  • http://{BLOCKED}7.{BLOCKED}3.in:8456/z/ad.txt
  • http://{BLOCKED}0.{BLOCKED}x.com/{unknown-0}.exe
  • http://{BLOCKED}1.{BLOCKED}x.com/{unknown-1}.exe
  • http://{BLOCKED}2.{BLOCKED}x.com/{unknown-2}.exe
  • http://{BLOCKED}3.{BLOCKED}x.com/{unknown-3}.exe
  • http://{BLOCKED}4.{BLOCKED}x.com/{unknown-4}.exe
  • http://{BLOCKED}5.{BLOCKED}x.com/{unknown-5}.exe
  • http://{BLOCKED}6.{BLOCKED}x.com/{unknown-6}.exe
  • http://{BLOCKED}7.{BLOCKED}x.com/{unknown-7}.exe
  • http://{BLOCKED}8.{BLOCKED}x.com/{unknown-8}.exe
  • http://{BLOCKED}9.{BLOCKED}x.com/{unknown-9}.exe
  • http://{BLOCKED}a.{BLOCKED}x.com/{unknown-10}.exe
  • http://{BLOCKED}b.{BLOCKED}x.com/{unknown-11}.exe
  • http://{BLOCKED}c.{BLOCKED}x.com/{unknown-12}.exe
  • http://{BLOCKED}d.{BLOCKED}x.com/{unknown-13}.exe
  • http://{BLOCKED}e.{BLOCKED}x.com/{unknown-14}.exe
  • http://{BLOCKED}f.{BLOCKED}x.com/{unknown-15}.exe
  • http://{BLOCKED}g.{BLOCKED}x.com/{unknown-16}.exe
  • http://{BLOCKED}h.{BLOCKED}x.com/{unknown-17}.exe
  • http://{BLOCKED}i.{BLOCKED}x.com/{unknown-18}.exe
  • http://{BLOCKED}j.{BLOCKED}x.com/{unknown-19}.exe

It deletes the initially executed copy of itself

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

9.298.03

FIRST VSAPI PATTERN DATE:

01 Aug 2012

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

Restart in Safe Mode

[ Learn More ]

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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ﾏｵﾍｳｹﾘｼ・ﾎ
    • ImagePath = "%Program Files%\smss.exe"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ﾏｵﾍｳｹﾘｼ・ﾎ
    • Type = "10"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ﾏｵﾍｳｹﾘｼ・ﾎ
    • Start = "2"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ﾏｵﾍｳｹﾘｼ・ﾎ
    • ErrorControl = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ﾏｵﾍｳｹﾘｼ・ﾎ
    • DisplayName = "System Service"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ﾏｵﾍｳｹﾘｼ・ﾎ
    • ObjectName = "LocalSystem"

Step 4

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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • ﾏｵﾍｳｹﾘｼ・ﾎ
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\Root
    • LEGACY_*00CF*00B5*00CD*00B3*00B9*00D8*00BC*00FC*00B7*00FE*00CE*00F1

Step 5

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