Finding a brute force attack or dictionary attack on Windows servers
Actually, it’s fairly easy to find out your Windowsservers is being hit with an attack.
Simply enable auditing of Logon Events in your Security Policy and look at the eventviewer and see what pops up.
Open your eventviewer and search for logon events named 4625 n Windows 7, Vista, 2008 , 2008 R2 or 529 on Windows server 2003.
Open up these events and look at the username used, the network source address and see if they are legitimate login attempts or not.
You could use for instance WHOIS to find out where the attack came from or traceroute or nslookup.
If you’re under attack you’ll be seing hundreds or thousand of failed logon attenpts, somteimes from a single IP address or in a more serious scenario, from hundreds or even thousands IP addresses at once. In some cases, such an attack is also just a way to hide the real purpose behind the attack which is to find out what securiy measures you have in place and to search for any vulnerabilities you may have in place that can be use to hack you later on. The attacker tries to ”hide in the noise” so to speak.
If it’s a single IP address it’s fairly easy just to block the attacker in your external firewall completely or in the local Windows firewall (assuming you’re awake and have seen the attack ) but, if it’s hundreds or thousands at once it becomes more or less impossible if you can’t automate it.
This is where Syspeace comes into play.
Syspeace automatically monitors, traces, blocks and reports failed logon events if they reach the criterias you’ve set up, for example ”If an attacker fails to login 10 times during 30 minutes, I want the attackers IP address to be blocked completely on all ports for 2 hours” or even ”If an IP address fails to login more than 10 times during 7 days, I want the attacker to be blocked ..”
If you’re under attack, the fastest and easiest way is to download the free trial of Syspeace, install it and simply start the Syspeace service and the attack will be blocked automatically within minutes.
At the moment, Syspeace supports Windows 2003, 2008, 2008 R2, 2008 SBS 2012 , SQL Server, Exchange Server, Citrix and more.
Out of the box.
And there’s a fully functional, free 30 day trial on the website.