Penetration Testing mailing list archives
RE: Testing large networks
From: "Randy Golly" <randy.golly () comcast net>
Date: Mon, 7 Mar 2005 10:54:35 -0600
Sounds like you are in the same situation as I run into. Nothing too specific up front, but nit picky on the back end once they start seeing results. I'd say your methodology is in line with needs to be done. I agree with running a nmap scan first then use the results in your Nessus scan instead of just using the Nessus scan for all. Speeds it up and also reduces false positives. I try to follow these steps and break up the hosts.to.test list on several scanning boxes if possible. We just did a client with 650 hosts and got through the scanning portion in a couple of days. Then about a week of wading and sorting through the results to kick out the obvious. 1. nmap -T Aggressive -sT -sR -O -v -v -p 1-65535 -iL hosts.to.test -oN clientname.tcp (or, some other meaningful name) --append_output - --max_hostgroup 1 --osscan_limit 2. After that completes, do a Nessus scan. Read the hosts.to.test file as the target list, and set the ports for the tcp scan to "1-65535". On the prefs screen you will need to point to the filename above you used that contains the results of the nmap scan (in this case, clientname.tcp). Of course use "enable all but dangerous" for the plugin selection. Good luck! ... RandyG -----Original Message----- From: Dan Rogers [mailto:pentestguy () gmail com] Sent: Saturday, March 05, 2005 10:05 AM To: pen-test () securityfocus com Subject: Testing large networks Hi list, In the last few months I have been asked to assess a number of fairly large networks, which have been addressed very inefficiently. So, usually this consists of one or two main networks with about 1000 devices, and ten or so remote sites connected by WAN links or VPN's. It's not uncommon for the HQ to have a class B (or worse) as their internal subnet, even though there are nowhere near that many hosts. The problem I have is that a lot of the owners of these networks don't really know what they want in terms of testing, and ask very generic questions - things like "we want to know where we are weakest" or even "we want to know whats on our network". A lot of the motivation for this testing is usually passed down from senor management who just want to feel are secure, so they tell their IT managers to get a pen test without knowing what it means. This means IT managers can't often tell me what they actually want to be tested. I'm effectively given a blank sheet, and free reign to approach the testing from any angle I choose. It is also not uncommon for there to be little or no useful documentation - so I rarely have a complete set of network diagrams from which to work. These engagements mostly range from seven to twenty working days. Usually the approach goes something like this. 1. Ask IT manager to identify critical network infrastructure (servers, routers, wireless access points, Domain Controllers) - chose a representative sample for review 2. Attempt to establish general network architecture using a network-mapping tool 3. Perform internal scanning of network using NMAP/Nessus or GFI LANguard 4. look for really obvious problems. E.g. public/private SNMP or default passwords, missing patches, well known open trojan ports Create report giving fairly high-level areas of concern, and remediation (e.g. patch management solution/strategy, segregate servers from workstations with firewalls, update default passwords/use strong password strategy) When I conduct the tests, time is usually very tight, and therefore scanning of internal networks is quite costly time wise (especially if there is a class A/B to scan). Following a methodology which recommends scanning in several different ways and checking TCP responses just isn't practical. Using something like nessus can yield hundreds and hundreds of pages of results, and wading through them looking for false-positives is also not practical. So how do you lot approach testing a lage network? Also, how do you decide what to report to the client on? Cheers Dan
Current thread:
- Testing large networks Dan Rogers (Mar 07)
- Re: Testing large networks Matthew Caston (Mar 07)
- RE: Testing large networks Randy Golly (Mar 07)
- Re: Testing large networks Anders Thulin (Mar 08)
- <Possible follow-ups>
- Re: Testing large networks Davi Ottenheimer (Mar 07)
- RE: Testing large networks Piskovatskov, Alexey (Mar 07)
- Re: Testing large networks Dhruv Soi (Mar 08)