Analysis by: Hazel Ann Poligratis
ALIASES:

Trojan-Spy.Win32.Ursnif.yzj (Kaspersky)

 PLATFORM:

Windows

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

  • Threat Type: Trojan Spy

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan Spy 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: 571,904 bytes
Memory Resident: Yes
Initial Samples Received Date: 21 May 2018

Arrival Details

This Trojan Spy 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 Trojan Spy drops a copy of itself in the following folders using different file names:

  • %Application Data%\Microsoft\{random 8 character string}\{random 8 character string}.exe

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Autostart Technique

This Trojan Spy adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random 8 character string} = %Application Data%\Microsoft\{random 8 character string}\{random 8 character string}.exe

Other System Modifications

This Trojan Spy modifies the following file(s):

  • %Application Data%\Mozilla\Firefox\Profiles\{random string}.default\prefs.js

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
EnableSPDY3_0 = 0

HKEY_CURRENT_USER\Software\AppDataLow\
Software\Microsoft\{GUID}
TorClient = {random values}

HKEY_CURRENT_USER\Software\AppDataLow\
Software\Microsoft\{GUID}
Client = {random values}

HKEY_CURRENT_USER\Software\AppDataLow\
Software\Microsoft\{GUID}
{GUID} = {random values}

Other Details

This Trojan Spy connects to the following possibly malicious URL:

  • http://{BLOCKED}o.cz/files/AZ.bin
  • http://www.{BLOCKED}o.cz/files/AZ.bin

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 14.266.02
FIRST VSAPI PATTERN DATE: 22 May 2018
VSAPI OPR PATTERN File: 14.267.00
VSAPI OPR PATTERN Date: 23 May 2018

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

 
  • In HKEY_CURRENT_USER\Software\AppDataLow\Software\Microsoft
    • {GUID}

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 8 character string} = %Application Data%\Microsoft\{random 8 character string}\{random 8 character string}.exe
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • EnableSPDY3_0 = "0"

Step 6

Restore deleted/modified files and/or registry entries from backup

*Note: Only Microsoft-related files/keys/values will be restored. If this malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

    %Application Data%\Mozilla\Firefox\Profiles\{random characters}.default\prefs.js

Step 7

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


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