Analysis by: Kerstan Josef Navarro
ALIASES:

Trojan-Spy.Win32.Zbot.mrys (Kaspersky), Trojan.Zbot (Symantec)

 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:

  • In the wild: Yes

  OVERVIEW

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.

  TECHNICAL DETAILS

File Size: 737,792 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 05 Jul 2013

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.

Installation

This spyware drops the following files:

  • %Application Data%\{random folder name}\{random file name and extension}

(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 copies of itself into the affected system:

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

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
{random CLSID} = "%Application Data%\{random folder name}\{random file name}.exe"

Other System Modifications

This spyware adds the following registry entries as part of its installation routine:

HKEY_CURRENT_USER\Software\Microsoft \
{random key}
{random value} = "{random data}"

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"

Download Routine

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

  • http://{BLOCKED}orrea.com/wp-admin/js/config.bin

  SOLUTION

Minimum Scan Engine: 9.300

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.SQI

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Search and delete these files

[ Learn More ]
There may be some component 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.
 
  • %Application Data%\{random folder name}\{random file name}.exe
  • %Application Data%\{random folder name}\{random file name and extension}

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
    • {random CLSID} = "%Application Data%\{random folder name}\{random file name}.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\{random key}
    • {random value} = {random data}
  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %WINDOWS%\explorer.exe = "%WINDOWS%\explorer.exe:*:Enabled:Windows Explorer"

Step 6

Reset Internet security settings

[ Learn More ]

Step 7

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


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