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Threat Encyclopedia

TSPY_ZBOT.AAMV

ANALYSIS BY

Anthony Joe Melgarejo


ALIASES:

PWS:Win32/Zbot (Microsoft), PWS-Zbot.gen.oj (McAfee), Win32/Spy.Zbot.YW trojan (ESET), Trj/Zbot.M (Panda)

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 part of the 64-bit ZBOT samples that have been spotted to target 64-bit systems during January 2014. Users affected by this malware may find the security of their systems compromised and their critical personal information stolen (such as their online banking credentials).

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:

1,245,328 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

28 Dec 2013

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 and 7.)

It drops the following files:

  • %Application Data%\{random folder name 2}\{random file name 2}.{random extension}
  • %Application Data%\{random folder name 2}\{random file name 2}.tmp

(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 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 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://{BLOCKED}tnywjwabxb.onion/zs/mimi.jpg

Information Theft

This spyware gathers the following data:

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

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)

Upon injecting codes to a certain process, it will check if that process is 64-bit. If it is, it will load its 64-bit version detected as TSPY64_ZBOT.AANP. Otherwise, it will just continue with the current 32-bit version.

It hides its dropped files and autostart registry.

It creates a process of svchost.exe for the execution of a hidden Tor Client service for the malware's C&C communication using the following command line:
"%System%\svchost.exe" --HiddenServiceDir "%APPDATA%\tor\hidden_service" --HiddenServicePort "1080 127.0.0.1:" --HiddenServicePort "5900 127.0.0.1:"

The malware will then inform its C&C server about its current configuration, letting the attacker perform remote commands to the affected system.

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

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

SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

10.508.01

FIRST VSAPI PATTERN DATE:

31 Dec 2013

VSAPI OPR PATTERN File:

10.509.00

VSAPI OPR PATTERN Date:

31 Dec 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.AAMV

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_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}

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TSPY_ZBOT.AAMV. 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 8

The following created registry key(s) 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 keys with a backup of the system registry. Note that the said key(s) 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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