BKDR_NEUREVT.AA

 Analysis by: Rika Joi Gregorio

 ALIASES:

Trojan:Win32/Neurevt.A(Microsoft), Trojan.Win32.Neurevt(Ikarus), a variant of Win32/Neurevt.A trojan(Eset)

 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: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet

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.

  TECHNICAL DETAILS

File Size:

225,792 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

08 Apr 2014

Payload:

Connects to URLs/IPs

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 drops the following copies of itself into the affected system and executes them:

  • %Program Files%\Common Files\Flash Update Client.{2227A280-3AEA-1069-A2DE-08002B30309D}\{random file name}.exe

(Note: %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 adds the following processes:

  • wuauclt.exe

It stays memory-resident by injecting codes into the following processes:

  • created 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\Policies\
Explorer\Run
Flash Update Client = "%Program Files%\Common Files\Flash Update Client.{2227A280-3AEA-1069-A2DE-08002B30309D}\{random file name}.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Flash Update Client = "%Program Files%\Common Files\Flash Update Client.{2227A280-3AEA-1069-A2DE-08002B30309D}\{random file name}.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Flash Update Client = "%Program Files%\Common Files\Flash Update Client.{2227A280-3AEA-1069-A2DE-08002B30309D}\{random file name}.exe"

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CLASSES_ROOT\CLSID\{CLSID}

HKEY_CLASSES_ROOT\CLSID\{CLSID}\
0BAC02C7

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\TaskManager

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\TaskManager
Task Service ID = "{hex value}"

It modifies the following registry entries:

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

(Note: The default value data of the said registry entry is 1.)

HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\
Java Update\Policy
EnableJavaUpdate = "0"

(Note: The default value data of the said registry entry is 1.)

Backdoor Routine

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

  • Download and execute files
  • Perform Slowloris flooding
  • Execute shell commands
  • Copy itself in removable drives
  • Open a URL
  • Uninstall/Update itself

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

  • http://{BLOCKED}tingprotection.info/icool/order.php

Information Theft

This backdoor gathers the following data:

  • Hardware information
  • Installed FTP software (CoreFTP, FileZilla, Flash FXP, FTP Commander, PuTTy, Smart FTP, WinSCP)
  • Java version
  • .NET version
  • Installed messaging software (Skype)
  • Installed anti-malware products
  • Installed browser
  • Operating system version
  • Installed software (Sysinternals, mIRC, Hex-Rays, Immunity Inc, CodeBlocks, 7-Zip, PrestoSoft, Nmap, Perl)

NOTES:

It creates the following registry to lower security settings:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\1
2500 = "3"

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\2
2500 = "3"

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3
2500 = "3"

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\4
2500 = "3"

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Net Framework setup\NDP

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

HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\CentralProcessor

It disables the following antivirus-related applications by adding the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\
Image File Execution Options\{application}
Debugger = {random characters}.exe

where {application} are as follows:

  • a2guard.exe
  • a2service.exe
  • a2start.exe
  • adaware.exe
  • ALUpdate.exe
  • arcaclean.exe
  • avastsvc.exe
  • avastui.exe
  • avcenter.exe
  • AVENGINE.exe
  • avgcfgex.exe
  • avgidsagent.exe
  • avgmfapx.exe
  • avgnt.exe
  • avguard.exe
  • avgui.exe
  • avgupd.exe
  • avgwdsvc.exe
  • AVK.exe
  • AVKTray.exe
  • avshadow.exe
  • BgScan.exe
  • BullGuard.exe
  • BullGuardBhvScanner.exe
  • BullGuardScanner.exe
  • BullGuardUpdate.exe
  • BullGuardUpdate2.exe
  • ccsvchst.exe
  • ccupdate.exe
  • CLPSLA.exe
  • coreFrameworkHost.exe
  • coreServiceShell.exe
  • drstrui.exe
  • egui.exe
  • ekrn.exe
  • epavjobs.exe
  • ForceField.exe
  • FProtTray.exe
  • FPWin.exe
  • fshoster32.exe
  • GDFirewallTray.exe
  • GDSC.exe
  • hijackthis.exe
  • housecalllauncher.exe
  • K7TSUpdT.exe
  • mbam.exe
  • mbamgui.exe
  • mcagent.exe
  • McPvTray.exe
  • mcshell.exe
  • mcshield.exe
  • McSvHost.exe
  • McUICnt.exe
  • mcupdate.exe
  • mcupdmgr.exe
  • MSASCui.exe
  • MsMpEng.exe
  • msseces.exe
  • niu.exe
  • op_mon.exe
  • pctsAuxs.exe
  • pctsGui.exe
  • pctsSvc.exe
  • PSANHost.exe
  • PSUAService.exe
  • PSUNMain.exe
  • RavMonD.exe
  • rcfp.exe
  • rsmain.exe
  • RsMgrSvc.exe
  • RsTray.exe
  • SBAMTray.exe
  • sbamui.exe
  • sguardxup.exe
  • spybotsd.exe
  • starter_avp.exe
  • symerr.exe
  • uiSeAgnt.exe
  • uiUpdateTray.exe
  • uiWatchDog.exe
  • Update.exe
  • update_tmp.exe
  • updater.exe
  • Upgrader.exe
  • usrreq.exe
  • uWinMgr.exe
  • WRSA.exe
  • zatray.exe

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

10.714.03

FIRST VSAPI PATTERN DATE:

08 Apr 2014

VSAPI OPR PATTERN File:

10.715.00

VSAPI OPR PATTERN Date:

09 Apr 2014

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 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_CLASSES_ROOT\CLSID
    • {CLSID}
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion
    • TaskManager

Step 4

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\Microsoft\Windows\CurrentVersion\Policies\Explorer\Run
    • Flash Update Client = "%Program Files%\Common Files\Flash Update Client.{2227A280-3AEA-1069-A2DE-08002B30309D}\{random file name}.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • Flash Update Client = "%Program Files%\Common Files\Flash Update Client.{2227A280-3AEA-1069-A2DE-08002B30309D}\{random file name}.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Flash Update Client = "%Program Files%\Common Files\Flash Update Client.{2227A280-3AEA-1069-A2DE-08002B30309D}\{random file name}.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\1
    • 2500 = "3"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\2
    • 2500 = "3"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3
    • 2500 = "3"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\4
    • 2500 = "3"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\{application}
    • Debugger = "{random characters}.exe"

Step 5

Restore this modified 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\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: ShowSuperHidden = "0"
      To: ShowSuperHidden = 1
  • In HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Update\Policy
    • From: EnableJavaUpdate = "0"
      To: EnableJavaUpdate = 1

Step 6

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