Modified by: Michael Cabel


TrojanSpy:Win32/Ursnif.gen!F (Microsoft); BehavesLike.Win32.Malware.mfc (mx-v) (Sunbelt)


Windows 2000, Windows XP, Windows Server 2003


  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes


Infection Channel: Dropped by other malware, Downloaded from the Internet

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It executes commands from a remote malicious user, effectively compromising the affected system.

It attempts to steal information, such as user names and passwords, used when logging into certain banking or finance-related websites.

It deletes the initially executed copy of itself.


File Size: 135,168 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 10 Oct 2012
Payload: Connects to URLs/IPs, Compromises system security, Steals information

Arrival Details

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.


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

  • %User Profile%\nah_{random}.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

It injects itself into the following processes running in the affected system's memory:

  • services.exe
  • csrss.exe
  • lsass.exe
  • winlogon.exe
  • smss.exe
  • svchost.exe
  • explorer.exe

Autostart Technique

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

nah_Shell = "%User Profile%\nah_{random}.exe"

Other System Modifications

This backdoor adds the following registry entries:

nah_id = "{random values}"

nah_options = "{random values}"

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • Delete self
  • Download Files
  • Update self
  • Shutdown
  • Change Version
  • Change Host
  • change reserved IP
  • Enable backdoor
  • Send Cookies
  • Receive Ccookies
  • Enable Remote Desktop
  • Execute files

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • http://{BLOCKED}.{BLOCKED}.29.152/system/
  • http://{BLOCKED}.{BLOCKED}.28.104/system/
  • http://{BLOCKED}.{BLOCKED}.217.59/system/

Information Theft

This backdoor attempts to steal information from the following banks and/or other financial institutions:

  • americanfunds
  • ameritrade
  • bankofamerica
  • capitalone
  • chase
  • citibank
  • etrade
  • fidelity
  • firstrade
  • huntington
  • ibanking-services
  • mandtbank
  • navyfcu
  • ncsecu
  • optionsxpress
  • paypal
  • regions
  • schwab
  • scottrade
  • sharebuilder
  • suntrust
  • tdbank
  • trade
  • usbank
  • wachovia
  • wellsfargo

Stolen Information

This backdoor sends the gathered information via HTTP POST to the following URL:

  • http://{BLOCKED}.{BLOCKED}.29.152/system/
  • http://{BLOCKED}.{BLOCKED}.29.152/system/
  • http://{BLOCKED}.{BLOCKED}.29.152/system/
  • http://{BLOCKED}.{BLOCKED}.28.104/system/
  • http://{BLOCKED}.{BLOCKED}.28.104/system/
  • http://{BLOCKED}.{BLOCKED}.28.104/system/
  • http://{BLOCKED}.{BLOCKED}.217.59/system/
  • http://{BLOCKED}.{BLOCKED}.217.59/system/
  • http://{BLOCKED}.{BLOCKED}.217.59/system/

Other Details

This backdoor deletes the initially executed copy of itself


It checks the existence of the following registry key:


If it exists, it gets the folder location of firefox.exe and creates the following file:

  • {folder location}\chrome\amba.jar

Once the file mentioned above is executed, it drops the following file:

  • {folder location}\chrome\amba.js - detected as JS_URSNIF.DJ

It also modifies the following file to point to amba.jar:

  • {folder path}\chrome\browser.manifest


Minimum Scan Engine: 9.200
VSAPI OPR PATTERN File: 9.453.00
VSAPI OPR PATTERN Date: 11 Oct 2012

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Remove malware files dropped/downloaded by BKDR_URSNIF.DN

Step 3

Identify and delete files detected as BKDR_URSNIF.DN using the Recovery Console

[ Learn More ]

Step 4

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
    • nah_Shell = "%User Profile%\nah_{random}.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion
    • nah_id = "{random values}"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion
    • nah_options = "{random values}"

Step 5

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. {folder location}\chrome\amba.jar

Step 6

Scan your computer with your Trend Micro product to delete files detected as BKDR_URSNIF.DN. 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 7

Restore these deleted files from backup

*Note: Only Microsoft-related 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.

{folder path}\chrome\browser.manifest

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