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TSPY_ZBOT.YUXZY

May 21, 2014
 Analysis by: Mark Joseph Manahan
 ALIASES:

Troj/Zbot-IDK (Sophos) ,Trojan horse Zbot.HVS (AVG) ,Trojan-Spy.Win32.Zbot.sgxn (Kaspersky) ,PWS:Win32/Zbot (Microsoft) ,PWSZbot-FYZ!CC179B5CBC89 (McAfee) ,Win32/Injector.BCRO trojan (Eset) ,Trojan.Zbot (Symantec) ,Trojan.Win32.Generic!BT (Sunbelt)

 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:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Spyware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware


This spyware may be dropped by other malware. It may be unknowingly downloaded by a user while visiting malicious websites.

It modifies the Internet Explorer Zone Settings.

  TECHNICAL DETAILS

Ports:

Random

File Size:

279,552 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

16 May 2014

Payload:

Downloads files

Arrival Details

This spyware may be dropped by other malware.

It may be unknowingly downloaded by a user while visiting malicious websites.

Installation

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

  • %User Profile%\Application Data\{random folder name 1}\{random file name}.exe

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

It drops the following files:

  • %User Profile%\Application Data\{random folder name 2}\{random file name}

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

It creates the following folders:

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

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

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} = "%User Profile%\Application Data\{random folder name 1}\{random file name}.exe"

Other System Modifications

This spyware adds the following registry entries:

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

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

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Privacy

HKEY_CURRENT_USER\Software\Microsoft\
{random}

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 spyware modifies the Internet Explorer Zone Settings.

Other Details

This spyware attempts to access the following websites to download files, which are possibly malicious:

  • http://{BLOCKED}businness.uk.nf/wp-security/plugins/modules/inc/lang/z/helps/file.php=config.bin
  • http://{BLOCKED}e-citadelhost/folder/file.php=config.bin

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

10.798.05

FIRST VSAPI PATTERN DATE:

16 May 2014

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.YUXZY

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\Internet Explorer
    • Privacy

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} = "%User Profile%\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"

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.
  • %User Temp%\m_editerror.tmp
  • %User Profile%\Application Data\{random folder name 2}

Step 7

Reset Internet security settings

[ Learn More ]

Step 8

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

 
  • In HKEY_CURRENT_USER\Software\Microsoft
    • {random}


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