Analysis by: Kathleen Notario

ALIASES:

PWS:Win32/Zbot.ZT (Microsoft); PWS-Zbot.gen.cc !! (Mcafee); Mal/Zbot-CX (Sophos); W32/Zbot.CX!tr.pws (Fortinet)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Spyware

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This spyware may connect to a remote URL to download its configuration file. The said file contains information where the malware can download an updated copy of itself, and where to send its stolen data. It also contains a list of targeted bank-related websites from which it steals information.

The URL where it connects to is randomly generated using a randomizing function, which is computed based on the system's current date. However, as of this writing, none of the sites are accessible.

It may also gather certain information from the affected system.

This spyware arrives as an attachment to email messages spammed by other malware/grayware or malicious users. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It attempts to steal information, such as user names and passwords, used when logging into certain banking or finance-related websites.

  TECHNICAL DETAILS

File Size: 190,464 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 19 Aug 2011
Payload: Downloads files, Connects to URLs/IPs

Arrival Details

This spyware arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

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

It may be downloaded from the following remote sites:

  • http://{BLOCKED}kplnnqsqe.org/news/?s={random}

Installation

This spyware drops the following files:

  • %Application Data%\{random1}\{random}.exe - copy of itself
  • %Application Data%\{random2}\{random}.{random} - encrypted file

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

It creates the following folders:

  • %Application Data%\{random1}
  • %Application Data%\{random2}

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

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • Global\{GUID}
  • Local\{GUID}

It is injected into the following processes running in memory:

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

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
GUID = "%Application Data%\{random1}\{random}.exe"

Other System Modifications

This spyware adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%Windows%\explorer.exe = "%Windows%\explorer.exe:*:Disabled:Windows Explorer"

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

HKEY_CURRENT_USER\Software\Microsoft\
{random}

Download Routine

This spyware accesses the following websites to download files:

  • http://{pseudorandom alpha characters}.biz/forum/
  • http://{pseudorandom alpha characters}.org/forum/
  • http://{pseudorandom alpha characters}.info/forum/
  • http://{pseudorandom alpha characters}.net/forum/
  • http://{pseudorandom alpha characters}.com/forum/

Information Theft

This spyware attempts to access a website to download a file which contains information where the Trojan can download an updated copy of itself, and where to send its stolen data. This configuration file also contains the following list of targeted bank-related websites from which it steals information:

  • http://assets.macys.com
  • http://marketandtarget.com
  • http://www.blogcdn.com
  • http://www.chase.com
  • http://www.gafringwirt.at
  • http://www.marketandtarget.com
  • https://*.ebanking-services.com/*/signin.aspx
  • https://banking.postbank.de
  • https://banking.sparda.de
  • https://chaseonline.chase.com
  • https://client.schwab.com
  • https://content.usaa.com
  • https://express.53.com
  • https://gif.juniper.com/images/barclaycardus
  • https://secure.americanexpress.com
  • https://signin.fiabusinesscard.com
  • https://static.my.commbank.com.au
  • https://wellsoffice.wellsfargo.coms
  • https://www.accountcentralonline.com
  • https://www.bbvanetcash.com
  • https://www.chase.com/personalData
  • https://www.commerzbank.de
  • https://www.discovercard.com
  • https://www.ezcardinfo.com
  • https://www.gotomycard.com
  • https://www.hsbccreditcard.com
  • https://www.ibsnetaccess.com
  • https://www.macys.com
  • https://www.myaccountaccess.com/onlineCard/static/elan/img
  • https://www.nordstromcard.com
  • https://www.partnercardservices.com
  • https://www.pnccardservicesonline.com
  • https://www.statementlook.com
  • https://www.suntrust.com

It attempts to steal information from the following banks and/or other financial institutions:

  • American Express
  • BBVA
  • Barclays
  • Blogcdn
  • Chase
  • CommBANK
  • Commerzbank
  • Discover Card
  • Elan Financial Services
  • FIA Card Services
  • Fifth Third
  • Gafringwirt
  • GoToMyCard
  • HSBC
  • Macy's
  • Market and Target
  • Nordstrom Card
  • PNC
  • Partner Card Services
  • Postbank
  • Schwab
  • Sparda
  • StatementLook
  • Suntrust
  • USAA
  • Wells Fargo
  • eZCardInfo

Stolen Information

This spyware sends the gathered information via HTTP POST to the following URL:

  • http://{BLOCKED}kplnnqsqe.org/news/?s={random}

NOTES:

It may connect to a remote URL to download its configuration file. The said file contains information where the malware can download an updated copy of itself, and where to send its stolen data. It also contains a list of targeted bank-related websites from which it steals information.

The URL where it connects to is randomly generated using a randomizing function, which is computed based on the system's current date. However, as of this writing, none of the sites are accessible.

It may also gather the following information from the affected system:

  • Data on Cookie files (URLs)
  • Email-related information such as account names, email addresses, passwords, server data, and server port
  • Email information stored in the user’s Windows Address Book (WAB) file

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.372.04
FIRST VSAPI PATTERN DATE: 19 Aug 2011

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

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

Step 3

Restart in Safe Mode

[ Learn More ]

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\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %Windows%\explorer.exe = "%Windows%\explorer.exe:*:Disabled:Windows Explorer"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • GUID = "%Application Data%\{random1}\{random}.exe"

Step 5

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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_CURRENT_USER\Software\Microsoft
    • {random}

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.
  • %Application Data%\{random1}
  • %Application Data%\{random2}

Step 7

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