Summary
Dasher.A is a worm that exploits a vulnerability in Microsoft Windows Distributed Transaction Coordinator (MS05-051).
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.
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
Installation to system
The worm's dropper is a self-extracing RAR archive which drops the following files:
- %windir%\Temp\SqlExp.exe
- %windir%\Temp\Sqlrep.exe
- %windir%\Temp\SqlScan.exe
- %windir%\Temp\Sqltob.exe
The file Sqltob.exe is the actual worm main file. Sqlrep.exe is utilty called "Replace Commander". SqlScan.exe is a port scan utilty and SqlExp.exe is a component that is used in MSDTC exploiting.
When the main file is run, it adds the following registry entry to ensure that it is started when a user logs on or the system is restarted:
- [HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run] "Windows Update" = "%windir%\Temp\Sqltob.exe"
The worm may also create the following files:
- %windir%\Temp\Result.txt
- %windir%\Temp\SqlScan.bat
These files are used in exploiting.
Spreading using MSTDC vulnerability
The worm scans for systems vulnerable to MSTDC (MS05-051) through TCP/1025. It constructs random addresses using a fixed list of A-class networks. If it finds a system responding to TCP SYN scan, it sends the exploit payload. The payload connects to remote address and waits for instructions. At the time of this writing, the remote server is not accessible. According to reports, the server may instruct the infected system to download and activate the worm's dropper.
Please see the following page for detailed information on the vulnerability:
https://www.microsoft.com/technet/security/Bulletin/MS05-051.mspx
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.