Dear All, The SLMail's smtp service (slsmtp.exe) is susceptible to a denial of service attack, whereby a remote attacker can telnet to port 25 and then issue any of the following commands, which will set the slsmtp.exe process running at 100%. send ( vrfy ( expn ( mail from: ( rcpt to: ( slsmtp.exe obviously doesn't like left brackets. After 30 mins without the high processor usage abating, I had to stop and restart the service. While the process was in this state, although I could telnet to port 25 and connect, I received no response from the smtp service. This attack is more likely to occur than the POP3 DoS due to the fact that if the mail server is accessible from the Internet then this can be launched by anyone from anywhere. As to a fix - I still haven't heard anything from Seattlelab about a patch. I have tried tweaking the registry but can't find a workaround there. Any ideas anyone? Cheers, Mnemonix http://www.infowar.co.uk/mnemonix http://www.diligence.co.uk
This archive was generated by hypermail 2b30 : Fri Apr 13 2001 - 14:17:19 PDT