BKDR_URSNIF.DN
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
OVERVIEW
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.
TECHNICAL DETAILS
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.
Installation
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:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
nah_Shell = "%User Profile%\nah_{random}.exe"
Other System Modifications
This backdoor adds the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion
nah_id = "{random values}"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion
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/prinimalka.py/command
- http://{BLOCKED}.{BLOCKED}.28.104/system/prinimalka.py/command
- http://{BLOCKED}.{BLOCKED}.217.59/system/prinimalka.py/command
Information Theft
This backdoor attempts to steal information from the following banks and/or other financial institutions:
- 53.com
- americanfunds
- ameritrade
- bankofamerica
- capitalone
- chase
- citibank
- etrade
- fidelity
- firstrade
- huntington
- ibanking-services
- mandtbank
- navyfcu
- ncsecu
- optionsxpress
- paypal
- pnc.com
- regions
- schwab
- scottrade
- sharebuilder
- suntrust
- tdbank
- trade
- usaa.com
- usbank
- wachovia
- wamu.com
- wellsfargo
Stolen Information
This backdoor sends the gathered information via HTTP POST to the following URL:
- http://{BLOCKED}.{BLOCKED}.29.152/system/prinimalka.py/options
- http://{BLOCKED}.{BLOCKED}.29.152/system/prinimalka.py/forms
- http://{BLOCKED}.{BLOCKED}.29.152/system/prinimalka.py/cookies
- http://{BLOCKED}.{BLOCKED}.28.104/system/prinimalka.py/options
- http://{BLOCKED}.{BLOCKED}.28.104/system/prinimalka.py/forms
- http://{BLOCKED}.{BLOCKED}.28.104/system/prinimalka.py/cookies
- http://{BLOCKED}.{BLOCKED}.217.59/system/prinimalka.py/options
- http://{BLOCKED}.{BLOCKED}.217.59/system/prinimalka.py/forms
- http://{BLOCKED}.{BLOCKED}.217.59/system/prinimalka.py/cookies
Other Details
This backdoor deletes the initially executed copy of itself
NOTES:
It checks the existence of the following registry key:
HKEY_CURRENT_USER\Software\Classes\FirefoxHTML\shell\open\command
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
SOLUTION
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 3
Identify and delete files detected as BKDR_URSNIF.DN using the Recovery Console
Step 4
Delete this registry value
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"
- nah_Shell = "%User Profile%\nah_{random}.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion
- nah_id = "{random values}"
- nah_id = "{random values}"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion
- nah_options = "{random values}"
- nah_options = "{random values}"
Step 5
Search and delete these files
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.
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