Hacking Exposed Web Applications, 3rd Edition [PDF]

Summary
Here on this page, we have provided the latest download link for Hacking Exposed Web Applications, 3rd Edition PDF. Please feel free to download it on your computer/mobile. For further reference, you can go to isecom.org

Hacking Exposed Web Applications, 3rd Edition Book

Another countermeasure against some automated attacks is to lock access when a certain number of failed attempts have been exceeded. Since such measures are only intended to lock out unskilled attackers, of course, you still need to have other lines of defense in place.

Linux can be extended to lock out user accounts after a certain number of failed login attempts by using the pam_tally module. This allows you to implement such a limit for all the services that rely on PAM. Therefore, this measure only affects the systems authentication library. Another approach is to deny access at the network level.

deny hosts is an example of such an application. It parses the log files of sshd and adds appropriate entries to /etc/hosts. deny, thus preventing hosts with too high of a fail count to connect to an SSH daemon again. Such tools also exist for other services, or they might be relatively easy to implement yourself.

Unfortunately, such automated lockouts have two drawbacks: There’s always a chance you might lock yourself out by accident. And with methods that block access on a network layer, if legitimate users need to connect from dynamic IP addresses, which most Internet providers offer to end-users, you might have problems. You need to carefully consider such limitations.