Analysis by: Jasen Sumalapao
ALIASES:

PWS:Win32/Zbot (Microsoft), Trojan.Gen (Symantec), W32/Pinkslipbot.gen.ay (NAI), Mal/EncPk-AEX (Sophos), Trojan.Win32.Generic!BT (Sunbelt), Gen:Variant.Barys.5161 (Bitdefender), W32/Krypt.AAOD!tr (Fortinet), Trojan-PWS.Win32.Zbot (Ikarus), a variant of Win32/Kryptik.AGSF trojan (NOD32), Trj/Sinowal.WXO (Panda)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:
 INFORMATION EXPOSURE:

  • Threat Type: Spyware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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

The dropped file is injected in all running processes.

It modifies the Internet Explorer Zone Settings.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size: 164,352 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 09 Aug 2012

Arrival Details

This spyware 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 spyware drops a copy of itself in the following folders using different file names:

  • %User Profile%\Application Data\{random folder}\{random filename}.exe

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

The dropped file is injected in all running processes.

Autostart Technique

This spyware creates the following registry entries to enable automatic execution of dropped component at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{GUID} = %User Profile%\Application Data\{random characters}\{random filename}.exe

Web Browser Home Page and Search Page Modification

This spyware modifies the Internet Explorer Zone Settings.

Other Details

This spyware deletes itself after execution.

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 9.312.02
FIRST VSAPI PATTERN DATE: 09 Aug 2012
VSAPI OPR PATTERN File: 9.313.00
VSAPI OPR PATTERN Date: 10 Aug 2012

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 the registry entry with an unknown data 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\Run
    • {GUID} = "%User Profile%\Application Data\{random characters}\{random filename}.exe"

Step 4

Reset Internet security settings

[ Learn More ]

Step 5

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