Analysis by: Jimelle Monteser
ALIASES:

Trojan:Win32/Neurevt.A (Microsoft), Win32/Neurevt.A trojan (NOD32), TR/Neurevt.A.65 (Antivir)

 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: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

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

It executes commands from a remote malicious user, effectively compromising the affected system.

It modifies Internet Explorer security settings. This puts the affected computer at greater risk, as it allows malicious URLs to be accessed by the computer.

  TECHNICAL DETAILS

File Size: 236,032 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 09 May 2013
Payload: Compromises system security, Connects to URLs/IPs, Steals information

Arrival Details

This backdoor 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 backdoor creates the following folders:

  • %Application Data%\Microsoft\Crypto
  • %Application Data%\Microsoft\Crypto\RSA
  • %Application Data%\Microsoft\Crypto\RSA\{Random}

(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 injects codes into the following process(es):

  • wuauclt.exe

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
ActiveUpdate = "{malware path}\{malware filename}"

Other System Modifications

This backdoor adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer
TaskbarNoNotification = "1"

HKEY_CURRENT_USER\Software\Win7zip
Uuid = "{random values}"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = "0"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\
rstrui.exe
Debugger = "{random}_.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\
hijackthis.exe
Debugger = "{random}_.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\
spybotsd.exe
Debugger = "{random}_.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\
housecalllauncher.exe
Debugger = "{random}_.exe"

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • Download files
  • Upload files
  • Copy itself in removable drives
  • Start or stop programs
  • Delete files

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • http://{BLOCKED}.{BLOCKED}.215.3:80
  • http://{BLOCKED}.{BLOCKED}.32.177:80

Web Browser Home Page and Search Page Modification

This backdoor modifies Internet Explorer zone settings.

Information Theft

This backdoor attempts to steal stored account information used in the following installed File Transfer Protocol (FTP) clients or file manager software:

  • CoreFTP
  • FileZilla
  • FlashFXP
  • FTP Commander
  • PuTTy
  • SmartFTP

Stolen Information

This backdoor sends the gathered information via HTTP POST to the following URL:

  • http://{BLOCKED}cio.com/wordpress/order.php

Other Details

This backdoor connects to the following URL(s) to check for an Internet connection:

  • update.microsoft.com
  • microsoft.com
  • windowsupdate.microsoft.com
  • google.com

NOTES:

It queries the following registry key to get the processor information:

HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\CentralProcessor

It queries the following registry key to get Microsoft Net Framework Version:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Net Framework setup\NDP

It scans the system for the following Antivirus and Security Related processes then terminates them:

  • APVXDWIN
  • ArcaBit
  • avast! Antivirus
  • Avira
  • AVP
  • Bdagent
  • BullGuard
  • emisoft anti-malware
  • ESET
  • fshoster
  • G Data Antivirus Tray Application
  • IStray
  • MSC
  • RsMgrSvc
  • Symantec
  • Trend Micro Titanium
  • WRSVC
  • ZoneAlarm

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 10.200.04
FIRST VSAPI PATTERN DATE: 06 Aug 2013
VSAPI OPR PATTERN File: 10.201.00
VSAPI OPR PATTERN Date: 07 Aug 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

Restart in Safe Mode

[ Learn More ]

Step 3

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\Win7zip
    • Uuid = "{random values}"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • ShowSuperHidden = "0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\rstrui.exe
    • Debugger = "{random}_.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\hijackthis.exe
    • Debugger = "{random}_.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\spybotsd.exe
    • Debugger = "{random}_.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\housecalllauncher.exe
    • Debugger = "{random}_.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer
    • TaskbarNoNotification = "1"

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.
  • %Application Data%\Microsoft\Crypto

Step 5

Reset Internet security settings

[ Learn More ]

Step 6

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


Did this description help? Tell us how we did.