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TSPY_ZBOT.PNR

January 28, 2014
 Analysis by: Nikko Tamana
 ALIASES:

Win32/Spy.Zbot.AAQ trojan (NOD32), Trojan.Zbot (Norton), Troj/Zbot-DUY (Sophos)

 PLATFORM:

Windows 2000, Windows XP (32-bit and 64-bit), Windows Server 2003, Windows Vista (32-bit and 64-bit), Windows 7 (32-bit and 64-bit)

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

  • Threat Type: Spyware

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware


This malware is the main payload of the file infector attack that was detected on January 2014. Users with systems affected by this malware may find their personal information stolen and their online banking accounts compromised.

To get a one-glance comprehensive view of the behavior of this Spyware, refer to the Threat Diagram shown below.

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 deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

180,000 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

20 Jan 2014

Payload:

Connects to URLs/IPs, Downloads files, Steals information

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 name 1}\{random file name 1}.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, 7, and 8.)

It drops the following files:

  • %Application Data%\gmon.out - Contains encrypted information (Non-malicious)
  • {Malware Path}\gmon.out - Contains encrypted information (Non-malicious)
  • %Application Data%\{random folder name 2}\{random file name 2}.{random extension}
  • %Application Data%\Microsoft\Address Book\{user name}.wab
  • %Application Data%\Microsoft\Address Book\{user name}.wab~

(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, 7, and 8.)

It creates the following folders:

  • %Application Data%\{random folder name 1}
  • %Application Data%\{random folder name 2}
  • %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, 7, and 8.)

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

  • Global\{GUID}
  • Local\{GUID}

It injects threads into the following normal process(es):

  • explorer.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%\{random folder name 1}\{random file name 1}.exe"

Other System Modifications

This Spyware adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
{random}

HKEY_CURRENT_USER\Software\Microsoft\
WAB

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Privacy
CleanCookies = "0"

Download Routine

This Spyware connects to the following URL(s) to download its configuration file:

  • http://dinos.{BLOCKED}i.me/file.php

Information Theft

This Spyware gathers the following data:

  • Data on cookie files (URLs)
  • FTP credentials
  • Online banking credentials
  • Flashplayer data
  • Personal digital cerificates

Stolen Information

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

  • http://dinos.{BLOCKED}i.me/file.php

Other Details

This Spyware connects to the following URL(s) to check for an Internet connection:

  • http://www.google.com/webhp

It connects to the following URL(s) to get the affected system's IP address:

  • http://checkip.dyndns.org

It deletes the initially executed copy of itself

NOTES:

The configuration file may contain the following information:

  • Download link to an updated copy of itself
  • Site(s) where it will send its stolen information
  • Download link to an updated copy of its configuration file
  • Configuration for stealing online banking account credentials (including targeted banks)

It prevents the execution of newly created processes of analysis tools such as the following:

  • ImPrec
  • LodPE
  • OllyDbg
  • WinHex
  • Stud PE
  • ProcDump
  • PESam

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:DNS #{random}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
%System%\ctfmon.exe = "%System%\ctfmon.exe:*:Enabled:DNS #{random}"

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

10.552.03

FIRST VSAPI PATTERN DATE:

20 Jan 2014

VSAPI OPR PATTERN File:

10.553.00

VSAPI OPR PATTERN Date:

21 Jan 2014

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 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.PNR

Step 3

Restart in Safe Mode

[ Learn More ]

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
    • WAB

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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %Windows%\Explorer.EXE = "%Windows%\Explorer.EXE:*:Enabled:DNS #{random}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %System%\ctfmon.exe = "%System%\ctfmon.exe:*:Enabled:DNS #{random}"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {GUID} = "%Application Data%\{random folder name 1}\{random file name 1}.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Privacy
    • CleanCookies = "0"

Step 6

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}
  • %Application Data%\Microsoft\Address Book

Step 7

Search and delete these files

[ Learn More ]
There may be some 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.
  • {Malware Path}\gmon.out

Step 8

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

Step 9

The following created files/folders/registry keys/registry entries cannot be identified by the user since there are no reference values in the created key. The only way it can be identified is by comparing the present system information with a backup. Note that the said components do not have to be deleted since it won't be harmful to the system.

  • HKEY_CURRENT_USER\Software\Microsoft\{random}


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