TROJ_DROPPR.XQ

December 06, 2013
 Analysis by: Nikko Tamana
 ALIASES:

Troj/Mdrop-FNZ (Sophos), Trojan horse Dropper.Generic8.AZNQ (AVG), Trojan-Clicker.Agent (Ikarus), Trojan-Downloader.JS.Zapchast.al (Kaspersky)

 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: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware

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:

485,941 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

04 Dec 2013

Payload:

Drops files, Terminates processes

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 file(s)/component(s):

  • %User Temp%\RarSFX0\update.bat - Executes the dropped copy
  • %User Temp%\RarSFX1\1.exe - Also detected as TROJ_DROPPR.XQ
  • %User Temp%\uDwn-FSRQ\config.bip - Contains configuration for 1.crx
  • %User Temp%\uDwn-FSRQ\whoviewsfm.xpi - Firefox extension
  • %User Temp%\uDwn-FSRQ\1.crx - Detected as JS_CHROMEX.AI
  • %User Temp%\uDwn-FSRQ\install.rdf - Contains installation information
  • %All Users Profile%\Application Data\1\1.crx - Detected as JS_CHROMEX.AI
  • %Application Data%\Mozilla\Firefox\Profiles\4wwmjcqo.default\extensions\hoverst@facebook.com\chrome.manifest
  • %Application Data%\Mozilla\Firefox\Profiles\4wwmjcqo.default\extensions\hoverst@facebook.com\content\prefman.js
  • %Application Data%\Mozilla\Firefox\Profiles\4wwmjcqo.default\extensions\hoverst@facebook.com\content\script-compiler-overlay.xul
  • %Application Data%\Mozilla\Firefox\Profiles\4wwmjcqo.default\extensions\hoverst@facebook.com\content\script-compiler.js
  • %Application Data%\Mozilla\Firefox\Profiles\4wwmjcqo.default\extensions\hoverst@facebook.com\content\skin\icon.png
  • %Application Data%\Mozilla\Firefox\Profiles\4wwmjcqo.default\extensions\hoverst@facebook.com\content\xmlhttprequester.js

It drops the following copies of itself into the affected system:

  • %User Temp%\RarSFX0\1.sfx.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.)

It creates the following folders:

  • %Application Data%\Mozilla\Firefox\Profiles\4wwmjcqo.default\extensions\hoverst@facebook
  • %All Users Profile%\Application Data\1
  • %User Temp%\RarSFX0
  • %User Temp%\RarSFX1
  • %User Temp%\uDwn-FSRQ

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.. %All Users Profile% is the All Users or Common profile folder, which is C:\Documents and Settings\All Users in Windows 2000, XP, and Server 2003, and C:\ProgramData in Windows Vista and 7.. %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 System Modifications

This Trojan adds the following registry entries as part of its installation routine:

HKLM\SOFTWARE\Google\
Chrome\Extensions\{random letters}
path = "%All Users Profile%\Application Data\1\1.crx"

HKLM\SOFTWARE\Google\
Chrome\Extensions\{random letters}
version = "1.0.0"

It adds the following registry keys as part of its installation routine:

HKCU\Software\Microsoft\
Windows\CurrentVersion\Explorer\
BitBucket
c =

HKLM\SOFTWARE\Google
Chrome =

HKLM\SOFTWARE\Google\
Chrome
Extensions =

HKLM\SOFTWARE\Google\
Chrome\Extensions
{random letters} =

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows
CurrentVersion =

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows\CurrentVersion
Internet Settings =

NOTES:

It terminates running Google Chrome and Mozilla Firefox processes. It then opens a new Google Chrome window.

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

10.452.08

FIRST VSAPI PATTERN DATE:

04 Dec 2013

VSAPI OPR PATTERN File:

10.453.00

VSAPI OPR PATTERN Date:

05 Dec 2013

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

Remove malware/grayware files dropped/downloaded by TROJ_DROPPR.XQ

    • JS_CHROMEX.AI

Step 3

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.
  • %Application Data%\Mozilla\Firefox\Profiles\4wwmjcqo.default\extensions\hoverst@facebook
  • %All Users Profile%\Application Data\1
  • %User Temp%\RarSFX0
  • %User Temp%\RarSFX1
  • %User Temp%\uDwn-FSRQ

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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\BitBucket
    • c
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows
    • CurrentVersion
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Google\Chrome\Extensions
    • {random letters}

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_DROPPR.XQ. 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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