Analysis by: Cris Nowell Pantanilla
ALIASES:

Virus.Win32.Expiro.w (Kaspersky); Virus:Win32/Expiro.AE (Microsoft)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: File infector

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This file infector may arrive as an infected file.

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 infects files by overwriting code in the entry point and saving the overwritten code in the virus body. It then appends the virus body to the host file.

It connects to a website to send and receive information.

It steals certain information from the system and/or the user.

  TECHNICAL DETAILS

File Size: Varies
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 21 May 2011
Payload: Modifies files, Connects to URLs/IPs, Steals information

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 adds the following mutexes to ensure that only one of its copies runs at any one time:

  • kkq-vx-mtx{number}
  • gazavat-svc

File Infection

This file infector infects files by overwriting code in the entry point and saving the overwritten code in the virus body. It then appends the virus body to the host file.

Backdoor Routine

This file infector connects to the following websites to send and receive information:

  • {BLOCKED}k.biz
  • {BLOCKED}k.ru
  • {BLOCKED}ys.com
  • {BLOCKED}g.cc
  • {BLOCKED}connection.ws
  • {BLOCKED}planets.ru
  • {BLOCKED}axclub.ru
  • {BLOCKED}bank.ru
  • {BLOCKED}romhugewar.ru
  • {BLOCKED}liketervana.com
  • {BLOCKED}t.com
  • www.{BLOCKED}k.ru
  • www.{BLOCKED}kx2011.ru
  • www.{BLOCKED}g.cc
  • www.{BLOCKED}connection.ws
  • www.{BLOCKED}tianbank.ca
  • www.{BLOCKED}t.com
  • www1.{BLOCKED}c.ca

Information Theft

This file infector steals the following information:

  • Windows Product ID
  • Drive Volume Serial Number
  • OS Version
  • User credentials
  • Information from Filezilla

Stolen Information

This file infector saves the stolen information in the following file:

  • %Application Data%\wsr18zt32.dll

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)

NOTES:
It may arrive as an infected file.

  SOLUTION

Minimum Scan Engine: 8.900
FIRST VSAPI PATTERN FILE: 8.170.08
FIRST VSAPI PATTERN DATE: 21 May 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

Search and delete this file

[ 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. %Application data%\ wsr18zt32.dll

Step 3

Scan your computer with your Trend Micro product to clean files detected as PE_EXPIRO.WA. 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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