TROJ_ZAPCHAST.FN

October 13, 2012
 ALIASES:

Backdoor:Win32/IRCbot, VirTool:Win32/HiddenRun.B, PWS:Win32/Passview, Tool:Win32/HideWindows, Backdo (Microsoft); Generic BackDoor!dmy (McAfee); Trojan.ADH (Symantec); ARC:CAB, PAK:[dmans.dll]:UPX, PAK:[fvist.com]:Molebox, PAK:[fvist.com]:UPX, PAK:[mansor.exe]:UPX, PA (Kaspersky); Trojan.Agent.ATV (fs) (Sunbelt); Gen:Trojan.Heur.4G3@r4RD5lgi (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan 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:

931,329 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

31 Aug 2012

Arrival Details

This Trojan 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 Trojan creates the following folders:

  • %User Temp%\pb2

(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.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
msngers = "%Desktop%\mosqino.com\fvist.com"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
msngers = "%User Temp%\pb2\fvist.com"

Other System Modifications

This Trojan deletes the following files:

  • %User Temp%\pb2.tmp

(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.)

It adds the following registry keys:

HKEY_CURRENT_USER\Software\mIRC

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Uninstall\
mIRC

HKEY_CURRENT_USER\Software\Microsoft\
Microsoft Agent

It adds the following registry entries:

HKEY_CURRENT_USER\Software\mIRC
DateUsed = "1323650588"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
mIRC
DisplayName = "mIRC"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
mIRC
UninstallString = "%User Temp%\pb2\fvist.com -uninstall"

HKEY_CURRENT_USER\Software\Microsoft\
Microsoft Agent
VoiceEnabled = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Microsoft Agent
UseVoiceTips = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Microsoft Agent
KeyHoldHotKey = "91"

HKEY_CURRENT_USER\Software\Microsoft\
Microsoft Agent
UseBeepSRPrompt = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Microsoft Agent
SRTimerDelay = "7d"

HKEY_CURRENT_USER\Software\Microsoft\
Microsoft Agent
SRModeID = "{random values}"

HKEY_CURRENT_USER\Software\Microsoft\
Microsoft Agent
EnableSpeaking = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Microsoft Agent
UseBalloon = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Microsoft Agent
UseCharacterFont = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Microsoft Agent
UseSoundEffects = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Microsoft Agent
SpeakingSpeed = "5"

HKEY_CURRENT_USER\Software\Microsoft\
Microsoft Agent
PropertySheetX = "f423f"

HKEY_CURRENT_USER\Software\Microsoft\
Microsoft Agent
PropertySheetY = "f423f"

HKEY_CURRENT_USER\Software\Microsoft\
Microsoft Agent
PropertySheetWidth = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Microsoft Agent
PropertySheetHeight = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Microsoft Agent
PropertySheetPage = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Microsoft Agent
CommandsWindowLeft = "ffffffff"

HKEY_CURRENT_USER\Software\Microsoft\
Microsoft Agent
CommandsWindowTop = "ffffffff"

HKEY_CURRENT_USER\Software\Microsoft\
Microsoft Agent
CommandsWindowWidth = "c8"

HKEY_CURRENT_USER\Software\Microsoft\
Microsoft Agent
CommandsWindowHeight = "c8"

HKEY_CURRENT_USER\Software\Microsoft\
Microsoft Agent
CommandsWindowLocationSet = "0"

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\PB1.tmp
  • %User Temp%\pb3.tmp
  • %User Temp%\pb2\orgs.reg

(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.)

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.200

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

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_CURRENT_USER\Software
    • mIRC
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall
    • mIRC
  • In HKEY_CURRENT_USER\Software\Microsoft
    • Microsoft Agent

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • msngers = "%Desktop%\mosqino.com\fvist.com"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • msngers = "%User Temp%\pb2\fvist.com"
  • In HKEY_CURRENT_USER\Software\mIRC
    • DateUsed = "1323650588"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\mIRC
    • DisplayName = "mIRC"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\mIRC
    • UninstallString = "%User Temp%\pb2\fvist.com -uninstall"
  • In HKEY_CURRENT_USER\Software\Microsoft\Microsoft Agent
    • VoiceEnabled = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Microsoft Agent
    • UseVoiceTips = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Microsoft Agent
    • KeyHoldHotKey = "91"
  • In HKEY_CURRENT_USER\Software\Microsoft\Microsoft Agent
    • UseBeepSRPrompt = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Microsoft Agent
    • SRTimerDelay = "7d"
  • In HKEY_CURRENT_USER\Software\Microsoft\Microsoft Agent
    • SRModeID = "{random values}"
  • In HKEY_CURRENT_USER\Software\Microsoft\Microsoft Agent
    • EnableSpeaking = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Microsoft Agent
    • UseBalloon = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Microsoft Agent
    • UseCharacterFont = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Microsoft Agent
    • UseSoundEffects = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Microsoft Agent
    • SpeakingSpeed = "5"
  • In HKEY_CURRENT_USER\Software\Microsoft\Microsoft Agent
    • PropertySheetX = "f423f"
  • In HKEY_CURRENT_USER\Software\Microsoft\Microsoft Agent
    • PropertySheetY = "f423f"
  • In HKEY_CURRENT_USER\Software\Microsoft\Microsoft Agent
    • PropertySheetWidth = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Microsoft Agent
    • PropertySheetHeight = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Microsoft Agent
    • PropertySheetPage = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Microsoft Agent
    • CommandsWindowLeft = "ffffffff"
  • In HKEY_CURRENT_USER\Software\Microsoft\Microsoft Agent
    • CommandsWindowTop = "ffffffff"
  • In HKEY_CURRENT_USER\Software\Microsoft\Microsoft Agent
    • CommandsWindowWidth = "c8"
  • In HKEY_CURRENT_USER\Software\Microsoft\Microsoft Agent
    • CommandsWindowHeight = "c8"
  • In HKEY_CURRENT_USER\Software\Microsoft\Microsoft Agent
    • CommandsWindowLocationSet = "0"

Step 5

Search and delete these files

[ 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.
  • %User Temp%\PB1.tmp
  • %User Temp%\pb3.tmp
  • %User Temp%\pb2\orgs.reg

Step 6

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.
  • %User Temp%\pb2

Step 7

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

Step 8

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %User Temp%\pb2.tmp


Did this description help? Tell us how we did.