Summary
Net-Worm:W32/Brontok.B attempts to propagate over removable media such as USB thumb drives. It may also attempt to connect to remote servers.Brontok.B disables certain features of the operating system.
Removal
Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.
To fix executable file associations after disinfection please download and run the following Registry fix:
A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:
Check for the latest database updates
First, check if your F-Secure security program is using the latest updates, then try scanning the file again.
Submit a sample
After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.
Note: If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.
Exclude a file from further scanning
If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.
Note: You need administrative rights to change the settings.
Technical Details
Execution
On execution, the first noticeable characteristic from this malware is the termination of applications such as CMD, regedit, and other EXE files. Processes with the following strings are terminated by this malware:
- ANT
- ASM
- AVAST
- BUG
- CONF
- CONSO
- DBG
- DETEC
- INSTALL
- KASP
- MCAFEE
- NOD
- NORTON
- NTVDM
- OPEN
- PLAY
- PROC
- REG
- REMOV
- SCAN
- SECUR
- SUPPO
- TASK
- UPDAT
- UPG
- VIR
- W32
- WALK
Furthermore, this malware will not perform any system changes if its filename is any of the following:
- AutoPro.exe
- mdefault.exe
- mcagent.exe
- mcshield.exe
During execution, the following files are dropped:
- C:\AUTORUN.INF
- C:\Documents and Settings\\Local Settings\Temp\~DF1A17.tmp
- C:\Documents and Settings\All Users\Start Menu\Programs\Startup\Empty.pif
- C:\WINDOWS\Autorun.inf
- C:\WINDOWS\Web\shell.exe
- C:\WINDOWS\winme.exe
- C:\winme.exe
Activity
This worm may open a browser attempting to connect to the following URLs:
- https://security.symantec.com
- https://www.symantec.com
Propagation
Brontok.B will create AUTORUN.INF files and copy itself to available removable media (USB drives) to allow itself to propagate.
Registry Modifications
Sets these values:
- [HKCR\batfile\shell\open\command] (default) = "C:\WINDOWS\web\shell.exe" "%1" %*
- [HKCR\comfile\shell\open\command] (default) = "C:\WINDOWS\web\shell.exe" "%1" %*
- [HKCR\exefile\shell\open\command] (default) = "C:\WINDOWS\web\shell.exe" "%1" %*
- [HKCR\piffile\shell\open\command] (default) = "C:\WINDOWS\web\shell.exe" "%1" %*
- [HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced] Hidden = 1 HideFileExt = 1 ShowSuperHidden = 1
- [HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System] DisableTaskMgr = 1 DisableRegistryTools = 1 DisableCMD = 1
- [HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer] Nofolderoptions = 1
- [HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\system] DisableTaskMgr = 1 DisableRegistryTools = 1
- [HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer] NoFolderOptions = 1
- [HKLM\SOFTWARE\Policies\Microsoft\Windows\Installer] DisableMSI = 1
- [HKLM\SOFTWARE\Policies\Microsoft\Windows NT\SystemRestore] DisableConfig = 1 DisableSR = 1
- [HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\ Shell = Explorer.exe "C:\WINDOWS\winme.exe" Userinit = C:\WINDOWS\System32\userinit.exe,C:\WINDOWS\winme.exe
- [HKLM\SYSTEM\ControlSet001\Control\SafeBoot\ AlternateShell = C:\WINDOWS\winme.exe
- [HKLM\SYSTEM\CurrentControlSet\Control\SafeBoot\ AlternateShell = C:\WINDOWS\winme.exe
Creates these keys:
- [HKCU\Software\Microsoft\Windows\CurrentVersion\Run\] winme = C:\WINDOWS\winme.exe
- [HKCR\lnkfile\shell\open\command\] (default) = "C:\WINDOWS\web\shell.exe" "%1" %*
Protect your devices from malware with F‑Secure Total
Protecting your devices from malicious software is essential for maintaining online security. F‑Secure Total makes this easy, helping you to secure your devices in a brilliantly simple way.
Award‑winning antivirus and malware protection
Online browsing, banking, and shopping protection
24/7 online identity and data breach monitoring
Unlimited VPN service to safeguard your privacy
Password manager with private data protection
Choose how many devices you want to protect to get started.
Free customer support
Cancel anytime
The trial does not obligate you to buy the product
After 30 days your subscription will renew automatically for one year at €69.99.
)
)
More Support
Community
Ask questions in our Community.
User guides
Check the user guide for instructions.
Contact Support
Chat with with or call an agent.
Submit a Sample
Submit a file or URL for analysis.