Microsoft pptp vpn vulnerabilities Exploits in Action

Protocol Description:
This attack targets GRE (protocol 47) sending a large quantity of 
malformed packets that the MS implementation is unable to handle correctly. 
How the Exploit Works:
The attacker sends the stream of malformed packets. Initially the CPU 
utilization will slowly increase and as more packets hit the server’s listening 
port, utilization will rise more quickly. The system’s ram utilization will climb as 
fast as 1 MB per second (depending on system hardware). If the attack is 
stopped/paused, the CPU will settle back down to normal, but the ram will 
remain “consumed”, though it will stop climbing. However, the attack is 
cumulative, unless the server is rebooted to clear the queue, so if the attacker 
later picks up the attack or performs it slowly over time, the system will keep 
consuming more memory, and CPU resources. Eventually, around 50% of 
available physical ram, the CPU utilization will suddenly jump up to 100%. The 
system is now unresponsive to most services, and cannot run any applications 
or be properly shutdown or rebooted.