BKDR_CHOPA.A
Windows 2000, Windows XP, Windows Server 2003
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Backdoor
Destructiveness: No
Encrypted:
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.
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 creates the following folders:
- %System Root%\DOCUME~1
- %System Root%\DOCUME~1\Wilbert
- %User Profile%\LOCALS~1
- %System Root%\Documents and Settings\Wilbert
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)
Other System Modifications
This backdoor modifies the following file(s):
- %User Profile%\Application Data\Microsoft
(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)
It deletes the following files:
- %User Temp%\tst6.tmp
- %User Temp%\tst8.tmp
- %User Temp%\tstD.tmp
- %User Temp%\tstF.tmp
- %User Temp%\tst11.tmp
- %User Profile%\Windows\NpshqRnL.xtr
(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)
It adds the following registry keys:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Wordpad
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Wordpad\Options
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Wordpad\Text
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Wordpad\RTF
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Wordpad\Word6
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Wordpad\Write
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Wordpad\IP
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Wordpad\Recent File List
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Wordpad\Settings
HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications
HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\
jds_snake
HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\
jds_snake\Recent File List
HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\
jds_snake\Settings
HKEY_CURRENT_USER\SOFTWARE\NpshqRnL
It adds the following registry entries:
HKEY_CURRENT_USER\Software\NpshqRnL
ServerStarted = "4/16/2014 14:44:39 PM"
HKEY_CURRENT_USER\Software\NpshqRnL
InstalledServer = "%User Temp%\stpass.exe"
Dropping Routine
This backdoor drops the following files:
- __tmp_rar_sfx_access_check_446781
- ico.ico
- israel.doc
- stpass.exe
- %User Startup%\ .lnk
- %User Temp%\ms4436.tmp
- %User Profile%\Microsoft\Crypto
- %User Profile%\Crypto\RSA
- %User Profile%\RSA\S-1-5-21-1645522239-1292428093-682003330-1003
- %User Temp%\stpass.exe
- %User Profile%\Windows\NpshqRnL.cfg
(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)
Other Details
This backdoor connects to the following possibly malicious URL:
- http://www.{BLOCKED}i.gov.lb:8080/1411.functions
- http://www.{BLOCKED}m.gov.lb:8080/1411.functions
- http://www.{BLOCKED}g.vizvaz.com:88/1411.functions
This report is generated via an automated analysis system.
SOLUTION
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
Delete this registry key
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\Applets
- Wordpad
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Wordpad
- Options
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Wordpad
- Text
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Wordpad
- RTF
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Wordpad
- Word6
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Wordpad
- Write
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Wordpad
- IP
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Wordpad
- Recent File List
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Wordpad
- Settings
- In HKEY_CURRENT_USER\Software
- Local AppWizard-Generated Applications
- In HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications
- jds_snake
- In HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\jds_snake
- Recent File List
- In HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\jds_snake
- Settings
- In HKEY_CURRENT_USER\SOFTWARE
- NpshqRnL
Step 3
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\NpshqRnL
- ServerStarted = "4/16/2014 14:44:39 PM"
- In HKEY_CURRENT_USER\Software\NpshqRnL
- InstalledServer = "%User Temp%\stpass.exe"
Step 4
Search and delete these components
- __tmp_rar_sfx_access_check_446781
- ico.ico
- israel.doc
- stpass.exe
- %User Startup%\ .lnk
- %User Temp%\ms4436.tmp
- %User Profile%\Microsoft\Crypto
- %User Profile%\Crypto\RSA
- %User Profile%\RSA\S-1-5-21-1645522239-1292428093-682003330-1003
- %User Temp%\stpass.exe
- %User Profile%\Windows\NpshqRnL.cfg
Step 5
Search and delete these folders
- %System Root%\DOCUME~1
- %System Root%\DOCUME~1\Wilbert
- %User Profile%\LOCALS~1
- %System Root%\Documents and Settings\Wilbert
Step 6
Scan your computer with your Trend Micro product to delete files detected as BKDR_CHOPA.A. 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 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.
- %User Profile%\Application Data\Microsoft
Step 8
Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.
- %User Temp%\tst6.tmp
- %User Temp%\tst8.tmp
- %User Temp%\tstD.tmp
- %User Temp%\tstF.tmp
- %User Temp%\tst11.tmp
- %User Profile%\Windows\NpshqRnL.xtr
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