TROJ_DLOADR.JWE

October 12, 2012
 ALIASES:

TrojanDownloader:Win32/Likseput.C (Microsoft); Generic.dx!bbrn (McAfee); Downloader (Symantec); ARC:RAR (Kaspersky); Trojan-Downloader.Win32.Small!cobra (v) (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:

163,710 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

25 Nov 2011

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:

  • %System Root%\DOCUME~1
  • %System Root%\DOCUME~1\ADMINI~1
  • %User Profile%\LOCALS~1

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
internet = "%User Temp%\internat.exe"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\WinRAR SFX

It adds the following registry entries:

HKEY_CURRENT_USER\Software\WinRAR SFX
C%%DOCUME~1%ADMINI~1%LOCALS~1%Temp = "%User Temp%"

Dropping Routine

This Trojan drops the following files:

  • __tmp_rar_sfx_access_check_45140
  • internat.exe

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://cost.{BLOCKED}sdaily.com/geodhs.htm

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

8.556.04

FIRST VSAPI PATTERN DATE:

07 Nov 2011

VSAPI OPR PATTERN File:

8.557.00

VSAPI OPR PATTERN Date:

08 Nov 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

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
    • WinRAR SFX

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • internet = "%User Temp%\internat.exe"
  • In HKEY_CURRENT_USER\Software\WinRAR SFX
    • C%%DOCUME~1%ADMINI~1%LOCALS~1%Temp = "%User Temp%"

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.
  • %System Root%\DOCUME~1
  • %System Root%\DOCUME~1\ADMINI~1
  • %User Profile%\LOCALS~1

Step 6

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.
  • __tmp_rar_sfx_access_check_45140
  • internat.exe

Step 7

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