TROJ_SMALL.NJL
TrojanDownloader:Win32/Small.gen!X (Microsoft); Downloader (Symantec); Trojan-Downloader.Win32.Dapato.qav (Kaspersky); Trojan-Downloader.Win32.Small (Sunbelt); Downloader.Rozena (AVG)
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Trojan
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This Trojan 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
33,792 bytes
EXE
Yes
02 May 2013
Arrival Details
This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
Autostart Technique
This Trojan adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
update = "%User Temp%\conhost.exe"
Other System Modifications
This Trojan deletes the following files:
- %System%\info.txt
- %System%\78515.txt
(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)
Dropping Routine
This Trojan drops the following files:
- %User Temp%\conhost.exe
- %Application Data%\config
- %System%\41281.txt
- %System%\41578.txt
- %System%\41875.txt
- %System%\42406.txt
- %System%\42875.txt
- %System%\43156.txt
- %System%\43796.txt
- %System%\44187.txt
- %System%\44484.txt
- %System%\45921.txt
- %System%\46218.txt
- %System%\46562.txt
- %System%\46906.txt
- %System%\47265.txt
- %System%\47703.txt
- %System%\48109.txt
- %System%\48515.txt
- %System%\52156.txt
- %System%\52484.txt
- %System%\52906.txt
- %System%\53218.txt
- %System%\53515.txt
- %System%\54562.txt
- %System%\54875.txt
- %System%\55171.txt
- %System%\55468.txt
- %System%\56671.txt
- %System%\56968.txt
- %System%\57265.txt
- %System%\57562.txt
- %System%\58500.txt
- %System%\58875.txt
- %System%\59156.txt
- %System%\59437.txt
- %System%\59890.txt
- %System%\60187.txt
- %System%\60484.txt
- %System%\60890.txt
- %System%\61187.txt
- %System%\61484.txt
- %System%\61890.txt
- %System%\62203.txt
- %System%\62500.txt
- %System%\62921.txt
- %System%\63203.txt
- %System%\63515.txt
- %System%\64875.txt
- %System%\65171.txt
- %System%\65546.txt
- %System%\66484.txt
- %System%\66921.txt
- %System%\70156.txt
- %System%\70453.txt
(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.. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.. %System% is the Windows system folder, which is usually C:\Windows\System32.)
Other Details
This Trojan connects to the following possibly malicious URL:
- http://update.{BLOCKED}g.ca/cgi/online.asp?{random characters}
- http://update.{BLOCKED}g.ca/cgi/anna-client-53.txt
- http://www.{BLOCKED}c.org.tw/images/temp_10.gif
This report is generated via an automated analysis system.
SOLUTION
9.300
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
Restart in Safe Mode
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\Microsoft\Windows\CurrentVersion\Run
- update = "%User Temp%\conhost.exe"
Step 4
Search and delete these components
- %User Temp%\conhost.exe
- %Application Data%\config
- %System%\41281.txt
- %System%\41578.txt
- %System%\41875.txt
- %System%\42406.txt
- %System%\42875.txt
- %System%\43156.txt
- %System%\43796.txt
- %System%\44187.txt
- %System%\44484.txt
- %System%\45921.txt
- %System%\46218.txt
- %System%\46562.txt
- %System%\46906.txt
- %System%\47265.txt
- %System%\47703.txt
- %System%\48109.txt
- %System%\48515.txt
- %System%\52156.txt
- %System%\52484.txt
- %System%\52906.txt
- %System%\53218.txt
- %System%\53515.txt
- %System%\54562.txt
- %System%\54875.txt
- %System%\55171.txt
- %System%\55468.txt
- %System%\56671.txt
- %System%\56968.txt
- %System%\57265.txt
- %System%\57562.txt
- %System%\58500.txt
- %System%\58875.txt
- %System%\59156.txt
- %System%\59437.txt
- %System%\59890.txt
- %System%\60187.txt
- %System%\60484.txt
- %System%\60890.txt
- %System%\61187.txt
- %System%\61484.txt
- %System%\61890.txt
- %System%\62203.txt
- %System%\62500.txt
- %System%\62921.txt
- %System%\63203.txt
- %System%\63515.txt
- %System%\64875.txt
- %System%\65171.txt
- %System%\65546.txt
- %System%\66484.txt
- %System%\66921.txt
- %System%\70156.txt
- %System%\70453.txt
Step 5
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_SMALL.NJL. 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 6
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.
- %System%\info.txt
- %System%\78515.txt
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