Help with custom vulnerability signature

[SDorsey]

Can someone provide documentation and insight in regards to creating custom IPS signatures based on the follow scenario?

Consider you have an FTP server. The USER command is vulnerable to buffer overflow. How does one create a custom signature to identify and block this activity?

The buffer and payload the attack sends could have 1000 variations.

[SDorsey]

Further info.. if the vulnerability is simple triggered by sending over 20 characters to it...

An attacker could send 100 A's. We could easily build a signature that watches for 100 \x41. But if they sent a payload of 100 \x42 and caused the crash, the custom signature would not match.

[dburns · Accepted solution]

Go here for Custom Signature help DevCenter

Dominic

[bat]

Hi SDorsey

I think such vulnerability should already be covered in the stock signatures in threat database. I searched through threat vault for some of the USER command overflow buffer vulnerabilities and found the following:

Does the threat database not cover the specific vulnerability you are looking for ?

Thanks

[SDorsey]

As oppose to being on a specific vulnerability, this is more a general inquire to try to understand how the IDS signatures work. In preparation for the need to create custom ones. And I know for sure that FTP USER overflow list is missing a few.

I created a new thread in DevCenter

General help with custom vulnerability signature