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PE_QUERVAR.B
Malware type: File infector
Destructive: No
Platform: Windows 2000, Windows XP, Windows Server 2003
Encrypted: Yes
In the wild: Yes

Overview


Infection Channel: Infects files, Downloaded from the Internet, Propagates via removable drives

This file infector arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It prepends its codes to target files. It adds infection markers to files.

It creates an event. However, as of this writing, the said sites are inaccessible.

Technical Details


File size: 565,272 bytes
File type: EXE
Memory resident: Yes
Initial samples received date: 08 Aug 2012
Payload: Terminates processes, Connects to URLs/IPs

Arrival Details

This file infector 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 file infector drops the following component file(s):

  • %Application Data%\{random folder name}\{random file name}.exe.ini
  • %Application Data%\{random folder name}\{random file name}.exe.lnk

(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.)

It drops and executes the following files:

  • %Application Data%\{random folder name}\{random file name}.exe - detected as PE_QUERVAR.B-O

(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.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
load = "%Application Data%\{random folder name}\{random file name}.exe.lnk"

File Infection

This file infector infects the following file types:

  • EXE
  • DOC
  • DOCX
  • XLS
  • XLSX

It prepends its codes to target files.

It adds infection markers to files.

Process Termination

This file infector terminates the following processes if found running in the affected system's memory:

  • taskmgr.exe

Other Details

Based on analysis of the codes, it has the following capabilities:

  • Attempts to connect to the following remote registry using Remote Registry Service: HKEY_CURRENT_USER\kaspersky
  • Update the malware copy.
  • Change the file names and folder name randomly.
  • Change the hash randomly on command.

It attempts to access the following websites to download files, which are possibly malicious:

  • http://www.update.{BLOCKED}t.com/windowsupdate/v6/thanks.aspx?{random}&pin={random}
  • http://{BLOCKED}dns.com/bl/in.php?{random}&pin={random}

It creates the following event(s):

  • "SayHellotomyLittleFriend"

However, as of this writing, the said sites are inaccessible.

NOTES:

Infected files are renamed depending on the file extension of the original file:

  • {original file name}.doc to {original file name}cod.scr
  • {original file name}.docx to {original file name}xcod.scr
  • {original file name}.xls to {original file name}slx.scr
  • {original file name}.xlsx to {original file name}xslx.scr

It searches for target drives by looking for drives without the System Volume Information folder to prevent infection of files in local hard drives.

Solution


Minimum scan engine: 9.200
First VSAPI Pattern File: 9.310.06
First VSAPI Pattern Release Date: 08 Aug 2012
VSAPI OPR Pattern Version: 9.311.00
VSAPI OPR Pattern Release Date: 08 Aug 2012

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

Scan your computer with your Trend Micro product and note files detected as PE_QUERVAR.B

Step 3

Restart in Safe Mode

[ Learn more ]

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_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows
    • load = "%Application Data%\{random folder name}\{random file name}.exe.lnk"

Step 5

Search and delete this folder

[ 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%\{random folder name}

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as PE_QUERVAR.B. 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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Analysis By: Jed Valderama

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