ALIASES:

PWS:Win32/Zbot.BD (Microsoft); Trojan.Zbot (Symantec); Trojan-Spy.Win32.Zbot.fck (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan.Spy.Zbot.LQ (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

Tamaño del archivo 351,744 bytes
Tipo de archivo EXE
Fecha de recepción de las muestras iniciales 03 Oct 2011

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 drops the following copies of itself into the affected system:

  • %System%\ntos.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

It creates the following folders:

  • %System%\wsnpoem
  • %User Profile%\Application Data\wsnpoem
  • %User Profile%\Application Data\VMware
  • %User Profile%\Microsoft\Dr Watson

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

Autostart Technique

This Trojan modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
userinit = "%System%\userinit.exe,%System%\ntos.exe,"

(Note: The default value data of the said registry entry is %System%\userinit.exe,.)

Other System Modifications

This Trojan deletes the following files:

  • %System%\ntos.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

It adds the following registry keys:

HKEY_CURRENT_USER\software\microsoft\
windows\currentversion\explorer\
{43BF8CD1-C5D5-2230-7BB2-98F22C2B7DC6}

HKEY_CURRENT_USER\software\microsoft\
windows\currentversion\explorer\
{35106240-D2F0-DB35-716E-127EB80A0299}

HKEY_CURRENT_USER\software\microsoft\
windows\currentversion\explorer\
{19127AD2-394B-70F5-C650-B97867BAA1F7}

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Network
UID = "BRIAN-75445F269_0006F1C5"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
{43BF8CD1-C5D5-2230-7BB2-98F22C2B7DC6}
{F710FA10-2031-3106-8872-93A2B5C5C620} = {random values}

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
{43BF8CD1-C5D5-2230-7BB2-98F22C2B7DC6}
{E716FA10-2031-AA96-8E72-93A205C5C62C} = {random values}

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
{35106240-D2F0-DB35-716E-127EB80A0299}
{F710FA10-2031-3106-8872-93A2B5C5C620} = {random values}

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
{35106240-D2F0-DB35-716E-127EB80A0299}
{E716FA10-2031-AA96-8E72-93A205C5C62C} = {random values}

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Network
UID = "BRIAN-75445F269_00071F6C"

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Network
UID = "BRIAN-75445F269_000748CE"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DrWatson
NumberOfCrashes = 1

(Note: The default value data of the said registry entry is 0.)

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
PCHealth\ErrorReporting\DW

Dropping Routine

This Trojan drops the following files:

  • %User Profile%\Dr Watson\drwtsn32.log
  • %User Profile%\Dr Watson\user.dmp

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}ame.cn/zzz1/poxcfg.bin

This report is generated via an automated analysis system.

  SOLUTION

Motor de exploración mínimo 9.200

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

Identify and delete files detected as TROJ_ZBOT.AGR using either the Startup Disk or Recovery Console

[ 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\microsoft\windows\currentversion\explorer
    • {43BF8CD1-C5D5-2230-7BB2-98F22C2B7DC6}
  • In HKEY_CURRENT_USER\software\microsoft\windows\currentversion\explorer
    • {35106240-D2F0-DB35-716E-127EB80A0299}
  • In HKEY_CURRENT_USER\software\microsoft\windows\currentversion\explorer
    • {19127AD2-394B-70F5-C650-B97867BAA1F7}

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 NT\CurrentVersion\Network
    • UID="BRIAN-75445F269_0006F1C5"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\{43BF8CD1-C5D5-2230-7BB2-98F22C2B7DC6}
    • {F710FA10-2031-3106-8872-93A2B5C5C620}={random values}
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\{43BF8CD1-C5D5-2230-7BB2-98F22C2B7DC6}
    • {E716FA10-2031-AA96-8E72-93A205C5C62C}={random values}
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\{35106240-D2F0-DB35-716E-127EB80A0299}
    • {F710FA10-2031-3106-8872-93A2B5C5C620}={random values}
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\{35106240-D2F0-DB35-716E-127EB80A0299}
    • {E716FA10-2031-AA96-8E72-93A205C5C62C}={random values}
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Network
    • UID="BRIAN-75445F269_00071F6C"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Network
    • UID="BRIAN-75445F269_000748CE"

Step 5

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DrWatson
    • From: NumberOfCrashes=1
      To: NumberOfCrashes=0
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: userinit="%System%\userinit.exe,%System%\ntos.exe,"
      To: userinit=%System%\userinit.exe,

Step 6

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.
  • %System%\wsnpoem
  • %User Profile%\Application Data\wsnpoem
  • %User Profile%\Application Data\VMware
  • %User Profile%\Microsoft\Dr Watson

Step 7

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 Profile%\Dr Watson\drwtsn32.log
  • %User Profile%\Dr Watson\user.dmp

Step 8

Scan your computer with your Trend Micro product to delete files detected as TROJ_ZBOT.AGR. 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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