Analysis by: Anthony Joe Melgarejo
ALIASES:

TrojanSpy:Win32/Ursnif!rfn (Microsoft),

 PLATFORM:

Windows

 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 spyware may be downloaded by other malware/grayware from remote sites. It may be dropped by other malware.

It connects to certain websites to send and receive information. It deletes itself after execution.

  TECHNICAL DETAILS

File Size: 352,256 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 25 Oct 2015
Payload: Connects to URLs/IPs

Arrival Details

This spyware may be downloaded by the following malware/grayware from remote sites:

  • http://{BLOCKED}l.by/aa.jpg

It may be dropped by the following malware:

  • W2KM_DRIDEX.YXS

Installation

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

  • %Application Data%\{8 random character folder name}\{8 random character file name}.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.)

It injects codes into the following process(es):

  • explorer.exe
  • opera.exe
  • chrome.exe
  • iexplore.exe
  • firefox.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
{8 random character value name} = "%Application Data%\{8 random character folder name}\{8 random character file name}.exe"

Other System Modifications

This spyware adds the following registry keys:

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

It adds the following registry entries:

HKEY_CURRENT_USER\Software\AppDataLow\
Software\Microsoft\{random GUID}
Install = "{encrypted file path of the dropped copy}"

HKEY_CURRENT_USER\Software\AppDataLow\
Software\Microsoft\{random GUID}
Client = "{hex value}"

Download Routine

This spyware downloads an updated copy of itself from the following website(s):

  • http://{BLOCKED}.{BLOCKED}.5.24/{4 digit number}{u or c}.exe

Information Theft

This spyware gathers the following data:

  • Online banking credentials
  • Keystroke logs

Other Details

This spyware connects to the following website to send and receive information:

  • {BLOCKED}lowdisallow.me
  • {BLOCKED}isallowallow.me
  • {BLOCKED}tagentdisa.me
  • {BLOCKED}otjclientcli.me
  • {BLOCKED}pcliallow.me
  • {BLOCKED}ntaxpalagent.me
  • {BLOCKED}lalaxp.mn
  • {BLOCKED}lientclient.me
  • {BLOCKED}liclient.me
  • {BLOCKED}nothing.me

It deletes itself after execution.

NOTES:

The random variables {8 random character value name}, {8 random character folder name} and {8 random character file name} are combinations of first four characters of the file name of a .DLL file and last four characters of another .DLL file found in the Windows system folder.

It uses domain generation algorithm (DGA) for its C&C servers. Once it connects to its C&C, it downloads its configuration file which contains the target online banking sites and web inject scripts.

  SOLUTION

Minimum Scan Engine: 9.800

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

Remove the malware/grayware file dropped/downloaded by TSPY_URSNIF.YXS. (Note: Please skip this step if the threat(s) listed below have already been removed.)

    • W2KM_DRIDEX.YXS

Step 4

Restart in Safe Mode

[ Learn More ]

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
    • {8 random character value name} = "%Application Data%\{8 random character folder name}\{8 random character file name}.exe"

Step 6

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\AppDataLow\Software\Microsoft
    • {random GUID}

Step 7

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