Analysis by: Maydalene Edsel Salvador

ALIASES:

VirTool:Win32/CeeInject.EF (Microsoft), Trojan.Zbot!gen35 (Norton), PWS-Zbot.gen.als (NAI), Mal/Katusha-J, Mal/Katusha-J (Sophos), LooksLike.Win32.ZboCheman.a (v) (Sunbelt), Gen:Heur.PIF.4 (BitDefender), W32/Yakes.AP!tr (Fortinet), Trojan-Ransom.Win32.PornoAsset (Ikarus)

 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:
 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.

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: 187,392 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 26 Apr 2013

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 the following copies of itself into the affected system:

  • %Application Data%\{RANDOM_FOLDER_NAME1}\{MALWARE_FILE_NAME}.exe

(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 drops the following files:

  • %Application Data%\Microsoft\Address Book\winxp.wab
  • %Application Data%\{RANDOM_FOLDER_NAME2}\{RANDOM_FILE_NAME}.{RANDOM_FILE_EXTENSION}

(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 creates the following folders:

  • %Application Data%\{RANDOM_FOLDER_NAME1}
  • %Application Data%\{RANDOM_FOLDER_NAME2}
  • %Application Data%\Microsoft\Address Book

(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.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{RANDOM_CLSID} = "%Application Data%\{RANDOM_FOLDER_NAME}\{MALWARE_FILE_NAME}.exe"

Other System Modifications

This spyware adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
WAB

HKEY_CURRENT_USER\Software\Microsoft\
{RANDOM_VALUES}

It creates the following registry entry(ies) to bypass Windows Firewall:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\GloballyOpenPorts\
List
{RANDOM_PORT_NUMBER}:TCP = "{RANDOM_PORT_NUMBER}:TCP:*:Enabled:TCP {RANDOM_PORT_NUMBER}"

Web Browser Home Page and Search Page Modification

This spyware modifies Internet Explorer zone settings.

Other Details

This spyware connects to the following possibly malicious URL:

  • http://{pseudorandom_domain_name}.ru/{random}.php
  • http://{pseudorandom_domain_name}.com/{random}.php

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 9.886.01
FIRST VSAPI PATTERN DATE: 29 Apr 2013
VSAPI OPR PATTERN File: 9.887.00
VSAPI OPR PATTERN Date: 30 Apr 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

Scan your computer with your Trend Micro product and note files detected as TSPY_ZBOT.EPK

Step 3

Restart in Safe Mode

[ Learn More ]

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%\{RANDOM_FOLDER_NAME1}
  • %Application Data%\{RANDOM_FOLDER_NAME2}
  • %Application Data%\Microsoft\Address Book

Step 5

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\Run
    • {RANDOM_CLSID} = "%Application Data%\{RANDOM_FOLDER_NAME}\{MALWARE_FILE_NAME}.exe"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\GloballyOpenPorts\List
    • {RANDOM_PORT_NUMBER}:TCP = "{RANDOM_PORT_NUMBER}:TCP:*:Enabled:TCP {RANDOM_PORT_NUMBER}"

Step 6

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
    • WAB
  • In HKEY_CURRENT_USER\Software\Microsoft
    • {RANDOM_VALUES}

Step 7

Reset Internet security settings

[ Learn More ]

Step 8

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