Analysis by: Rika Joi Gregorio

ALIASES:

PWS-Zbot-FAZB(McAfee), Win32/Spy.Zbot.AAU trojan(Eset)

 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: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware

This spyware may be dropped by other malware.

It is injected into all running processes to remain memory resident.

It does not have any propagation routine.

It does not have any backdoor routine.

  TECHNICAL DETAILS

File Size: 235,008 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 09 May 2013

Arrival Details

This spyware may be dropped by the following malware:

  • TROJ_ARTIEF.FIFI

Installation

This spyware drops the following copies of itself into the affected system and executes them:

  • %Application Data%\{random folder}\{random}.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\{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 and 7.)

It drops and executes the following files:

  • %User Temp%\tmp{random}.bat - Used to delete its initially executed copy (Already detected as BAT_VOBFUS.SM)

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It creates the following folders:

  • %Application Data%\{random folder}
  • %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.)

It is injected into all running processes to remain memory resident.

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

  • Global\{GUID}
  • Local\{GUID}

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}\{random}.exe"

Other System Modifications

This spyware adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
{random}

HKEY_CURRENT_USER\Software\Microsoft\
WAB

HKEY_CURRENT_USER\Software\Microsoft\
WAB\WAB4

HKEY_CURRENT_USER\Software\Microsoft\
WAB\WAB4\Wab File Name

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
{random}
{random} = "{random}"

HKEY_CURRENT_USER\Software\Microsoft\
WAB\WAB4
OlkContactRefresh = "0"

HKEY_CURRENT_USER\Software\Microsoft\
WAB\WAB4
OlkFolderRefresh = "0"

HKEY_CURRENT_USER\Software\Microsoft\
WAB\WAB4\Wab File Name
(Default) = "%Application Data%\Microsoft\Address Book\{user name}.wab"

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

bypass firewall HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\GloballyOpenPorts\
List
21047:UDP = "21047:UDP:*:Enabled:UDP 21047"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\GloballyOpenPorts\
List
21814:TCP = "21814:TCP:*:Enabled:TCP 21814"

Propagation

This spyware does not have any propagation routine.

Backdoor Routine

This spyware does not have any backdoor routine.

NOTES:

The configuration file may contain URLs where it downloads an updated copy of itself and where it sends its gathered information. It may also contain URLs of its target online banking and finance-related sites from where it steals the information.

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

This spyware connects to random generated IP addresses.

This spyware sends out DNS queries to a randomized domain name with the following extensions:

  • .info
  • .com
  • .biz
  • .org
  • .net
  • .ru

It connects to randomized domain name with the following format:

  • {pseudorandom characters}.{extension}

It does not have rootkit capabilities.

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 9.908.02
FIRST VSAPI PATTERN DATE: 09 May 2013
VSAPI OPR PATTERN File: 9.909.00
VSAPI OPR PATTERN Date: 10 May 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

Remove malware/grayware files that dropped/downloaded TSPY_ZBOT.FIFI

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
    • {random}
  • 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}\{random}.exe"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\GloballyOpenPorts\List
    • 21047:UDP = "21047:UDP:*:Enabled:UDP 21047"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\GloballyOpenPorts\List
    • 21814:TCP = "21814:TCP:*:Enabled:TCP 21814"

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%\{random folder}
  • %Application Data%\Microsoft\Address Book

Step 7

Search and delete this file

[ 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.
  • %User Temp%\tmp{random}.bat

Step 8

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

NOTES:

The created registry key HKEY_CURRENT_USER\Software\Microsoft\{random} cannot be identified by the users 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 if the users have one. Note that the key,{random} need not to be deleted since it won't cause the user system any harm.


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