Penetration Testing mailing list archives
Re: Evading IDS?
From: Rogan Dawes <lists@NO_dawes.SPAM_za.net>
Date: Fri, 19 Mar 2004 18:17:01 +0100
One other thing to consider, if it is a Cisco (Netranger) IDS, is that the shun list is generally only 100 items long. (This applied to a version I tested a couple of years ago, YMMV)
If you generate a large amount of bogus traffic that would get blocked (maybe by aliasing 100 interfaces to eth0, and nikto from each of them one ofter another), then after about 100 IP's, the IDS will be unable to add any more IPs to the shun list. Any new IP's that generate traffic that would normally be shunned will not be shunned, because the list is unable to accept any more entries.
You will be able to run your Nikto from a new IP address so long as you do it within the shun period when your 100 IP's are already shunned.
Might be worth exploring. Regards, Rogan Golomb, Gary wrote:
As far as already available tools go, use fragroute with the PAWS/wrapped sequencing chaffing options. Don't bother with the fragmentation options - you'll probably just run into the same problem. This could be used together with overlapping and out-of-order segments with some lapses in timing. (The fragroute man page is well written and covers all this stuff.) The only caveat is that you'll need to know how the end host will handle reassembly of your packets. A good way to test is to set up fragroute, send completely benign/normal requests though it, and see if you get replies. In reality, you'll get limited mileage with application-layer encoding against most IDSs, *especially* when it comes to http. (Not that it's completely ineffective. There are justeasier alternatives available IMO.)-gary-----Original Message From: Mark G. SpencerI've come across what I assume is an IDS during some network reconnaissance. I am able to run nmap (connect scan, default ports) against the entire target class C in question without any problems, but when I run Nikto against any of the webservers, Nikto output dies just after the trace/track method information and I am then unable to access anything on thetargetclass C for a set period of time - at least fifteen minutes. If I move to a different netblock, I can access the target class Cagain.. well, until I run Nikto. ;) It looks like all the routing and VPN gear on the target class C isCiscobased, so I'll make an assumption for now that the IDS is also Cisco. Any advice on how to evade the IDS? I know Nessus and Nikto offer a variety of IDS evasion techniques, but am I correct in assuming that a vendorsuchas Cisco (or any large vendor) has taken well-known evasion techniques into account? I will try different combinations of evasion techniquestodayand hopefully won't run out of open class C IP addresses on my network asIcontinue getting 15min+ blacklisted. Thanks for the advice, Mark------------------------------------------------------------------------ -- This space for rent. Only two spots left, so hurry! Have you ad placed in all my emails for one low monthly fee! Credit Card payments nowaccepted. -------------------------------------------------------------------------- --------------------------------------------------------------------------- Ethical Hacking at the InfoSec Institute. Mention this ad and get $545 off any course! All of our class sizes are guaranteed to be 10 students or less to facilitate one-on-one interaction with one of our expert instructors. Attend a course taught by an expert instructor with years of in-the-field pen testing experience in our state of the art hacking lab. Master the skills of an Ethical Hacker to better assess the security of your organization. Visit us at: http://www.infosecinstitute.com/courses/ethical_hacking_training.html ----------------------------------------------------------------------------
-- Rogan Dawes email: lists AT dawes DOT za DOT net "Using encryption on the Internet is the equivalent of arranging an armored car to deliver credit card information from someone living in a cardboard box to someone living on a park bench." - Gene Spafford --------------------------------------------------------------------------- Ethical Hacking at the InfoSec Institute. Mention this ad and get $545 off any course! All of our class sizes are guaranteed to be 10 students or less to facilitate one-on-one interaction with one of our expert instructors. Attend a course taught by an expert instructor with years of in-the-field pen testing experience in our state of the art hacking lab. Master the skills of an Ethical Hacker to better assess the security of your organization. Visit us at: http://www.infosecinstitute.com/courses/ethical_hacking_training.html ----------------------------------------------------------------------------
Current thread:
- Evading IDS? Mark G. Spencer (Mar 18)
- RE: Evading IDS? Matt Foster (Mar 19)
- Re: Evading IDS? Al Smolkin (Mar 19)
- RE: Evading IDS? Rob Shein (Mar 19)
- RE: Evading IDS? Antonio Varni (Mar 21)
- RE: Evading IDS? Rob Shein (Mar 19)
- RE: Evading IDS? Jerry Shenk (Mar 19)
- Re: Evading IDS? Antonio Varni (Mar 19)
- <Possible follow-ups>
- RE: Evading IDS? Golomb, Gary (Mar 19)
- Re: Evading IDS? Rogan Dawes (Mar 19)
- RE: Evading IDS? Mark G. Spencer (Mar 22)
- RE: Evading IDS? Billy Dodson (Mar 19)
- RE: Evading IDS? Levinson, Karl (Mar 19)
- RE: Evading IDS? Mark G. Spencer (Mar 19)
- RE: Evading IDS? Gary E. Miller (Mar 21)
- RE: Evading IDS? Mark G. Spencer (Mar 19)
- RE: Evading IDS? Eric McCarty (Mar 19)
- RE: Evading IDS? Billy Dodson (Mar 21)