TROJ_ZBOT.ESF

 Analysis by: Roland Marco Dela Paz

 ALIASES:

Trojan-Spy.Win32.Zbot.bxam (Kaspersky); Mal/Zbot-DE (Sophos)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 200

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW


This Trojan adds registry entries to disable Internet Explorer (IE).

This Trojan modifies the Internet Explorer Zone Settings.

It steals certain information from the system and/or the user.

  TECHNICAL DETAILS

File Size:

218,112 bytes

File Type:

PE

Memory Resident:

Yes

Initial Samples Received Date:

18 Jul 2011

Payload:

Bypasses Windows Firewall, Steals information, Disables Internet Explorer

Arrival Details

This Trojan may be downloaded from the following remote sites:

  • http://{BLOCKED}hcheckstart.com/large.exe

Installation

This Trojan adds the following folders:

  • %Application Data%\{random folder name 1}
  • %Application Data%\{random folder name 2}

(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 injects itself into the following processes running in the affected system's memory:

  • explorer.exe
  • taskhost.exe
  • taskeng.exe
  • Dwm.exe
  • wscntfy.exe
  • ctfmon.exe
  • rdpclip.exe

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{GUID} = %Application Data%\{random folder name 1}\{random file name}.exe

It drops the following files:

  • %Application Data%\{random folder name 1}\{random file name}.exe - copy of itself
  • %Application Data%\{random folder name 2}\{random file name} - contains encrypted stolen data

(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.)

Other System Modifications

This Trojan adds the following registry keys as part of its installation routine:

HKEY_CURRENT_USER\Software\Microsoft\
{random characters}

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

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%Windows%\EXPLORER.EXE = "%Windows%\EXPLORER.EXE:*:Enabled:Windows Explorer"

Web Browser Home Page and Search Page Modification

This Trojan modifies the Internet Explorer Zone Settings.

Information Theft

This Trojan monitors the Internet Explorer (IE) activities of the affected system, specifically the address bar. It recreates a legitimate website with a spoofed login page if a user visits banking sites with the following strings in the address bar and/or title bar:

  • https*/ach/*
  • https*/wire/*
  • https*/wires/*
  • https*53.com*
  • https*banking-services.com*
  • https*bankofamerica.com*
  • https*bbt.com*
  • https*bnymellon*
  • https*brdoffice*
  • https*business.hsbc*
  • https*businessonline.tdbank.com*
  • https*capitalone.com*
  • https*capitalonebank*
  • https*cashplus*
  • https*chase.com*
  • https*citigroup.com*
  • https*cmserver*
  • https*comerica.com*
  • https*directnet*
  • https*ebc_ebc*
  • https*enternetbank*
  • https*firstplacebankecomm*
  • https*fiservsa4*
  • https*fnbgranbury*
  • https*fremontnational*
  • https*goldleaf*
  • https*gs.com/*
  • https*gsfundadmin.com/*
  • https*hewitt.com*
  • https*hsbcnet*
  • https*iebanking*
  • https*internetbanking*
  • https*jpmorgan.com*
  • https*jpmorganchase*
  • https*key.com*
  • https*morganstanley*
  • https*mphro.com*
  • https*northerntrust.com*
  • https*onlinecashmanagement*
  • https*pnc.com*
  • https*pncbank.com*
  • https*raiffeisendirect*
  • https*raiffeisenonline*
  • https*rbc*
  • https*rbs.com*
  • https*regions.com*
  • https*scotiabank*
  • https*secure.ally.com*
  • https*singlepoint.usbank.com*
  • https*statestreet.com*
  • https*suntrust*
  • https*svbconnect*
  • https*tdcommercialbanking*
  • https*unicreditbank*
  • https*volksbankromania*
  • https*wachovia.com*
  • https*webcashmgmt*
  • https*wellsfargo.com*

It accesses the following site to download its configuration file:

  • http://{BLOCKED}thcheckstart.com/product-specs-9.html
  • http://{BLOCKED}ns.com/ban.rmftl
  • http://{BLOCKED}minute.com/ban.dtld

It steals the following information:

  • Personal certificates (MY)
  • FTP credentials for the following FTP applications:
    • FlashXP
    • Ghisler
    • IPSwitch
    • Filezilla
    • FTPFar
    • WinSCP
    • FTPCommander
    • CoreFTP
    • SmartFTP
    • Flashplayer data
  • Internet session cookies

Drop Points

Stolen information is uploaded to the following websites:

  • http://{BLOCKED}hcheckstart.com/rss233.php

Variant Information

This Trojan has the following MD5 hashes:

  • dfbee86af1738e9819708f5fca9e7dc5

It has the following SHA1 hashes:

  • 17590d6edba7f2c81487d40b3bdca6bc7d97180e

NOTES:

Adds the following registry entries to disable Internet Explorer (IE):

HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\PhishingFilter
Enabled = 0
EnabledV8 = 0

  SOLUTION

Minimum Scan Engine:

8.900

VSAPI OPR PATTERN File:

8.299.00

VSAPI OPR PATTERN Date:

18 Jul 2011

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 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} = %Application Data%\{random folder name 1}\{random file name}.exe
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %Windows%\EXPLORER.EXE = %Windows%\EXPLORER.EXE:*:Enabled:Windows Explorer
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\PhishingFilter
    • Enabled = 0
    • EnabledV8 = 0

Step 4

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
    • {random characters}

Step 5

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.
  • %Application Data%\{random folder name 1}
  • %Application Data%\{random folder name 2}

Step 6

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