Analysis by: Sabrina Lei Sioting

ALIASES:

TrojanDropper:Win32/Apropos.A (Microsoft), Spyware.Apropos (Symantec), Trojan.Win32.Apropo (fs) (Sunbelt), Adware/Apropo (Fortinet),

 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:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:
 INFORMATION EXPOSURE:

  • Threat Type: Adware

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This adware 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: 1,755,800 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 07 Apr 2011

Arrival Details

This adware 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 adware drops the following files:

  • %User Temp%\~compoundinst0\auto_update_loader.exe
  • %Program Files%\CxtPls\ace.dll
  • %Program Files%\CxtPls\AI_12-02-2013.log
  • %Program Files%\CxtPls\atl.dll
  • %Program Files%\CxtPls\CxtPls.dll
  • %Program Files%\CxtPls\CxtPls.exe
  • %Program Files%\CxtPls\data.bin
  • %Program Files%\CxtPls\libexpat.dll
  • %Program Files%\CxtPls\ProxyStub.dll
  • %Program Files%\CxtPls\uninstaller.exe
  • %Program Files%\CxtPls\WinGenerics.dll
  • %system%\ipcir.exe
  • %system%\ippdec.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.. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)

It creates the following folders:

  • %User Temp%\~compoundinst0
  • %Program Files%\CxtPls

(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.. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)

Other System Modifications

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

HKEY_LOCAL_MACHINE\SOFTWARE\Apropos

HKEY_LOCAL_MACHINE\SOFTWARE\Apropos\
Client

HKEY_LOCAL_MACHINE\SOFTWARE\AutoLoader

HKEY_LOCAL_MACHINE\SOFTWARE\AutoLoader\
EnvoloAutoUpdater

HKEY_LOCAL_MACHINE\SOFTWARE\Envolo

Download Routine

This adware connects to the following website(s) to download and execute a malicious file:

  • http://{BLOCKED}ad.contextplus.net/shared/AutoUpdaterInstaller.exe

It saves the files it downloads using the following names:

  • %User Temp%\auf0.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.)

  SOLUTION

Minimum Scan Engine: 9.300
SSAPI PATTERN File: 1.164.28
SSAPI PATTERN Date: 07 Apr 2011

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 terminate files detected as ADW_APROPOS.L

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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. 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_LOCAL_MACHINE\SOFTWARE
    • Apropos
  • In HKEY_LOCAL_MACHINE\SOFTWARE
    • AutoLoader
  • In HKEY_LOCAL_MACHINE\SOFTWARE
    • Envolo

Step 4

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.
%User Temp%\~compoundinst0
%Program Files%\CxtPls

Step 5

Search and delete this file

[ Learn More ]
There may be some 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.
%System%\ipcir.exe
%System%\ippdec.exe
%User Temp%\auf0.exe

Step 6

Scan your computer with your Trend Micro product to delete files detected as ADW_APROPOS.L. 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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