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Re: Client DDoS requests, ideas?
From: Jon Kibler <Jon.Kibler () aset com>
Date: Mon, 14 Jul 2008 19:28:28 -0400

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Erin Carroll wrote:
Jon,

Thanks for the reply. This wasn't a question specific to any client.

However, in some cases in the past clients with very narrow external
exposure have asked for this kind of testing. Fragmentation,
Amplification, protocol & app attacks either weren't effective or the
client's existing countermeasures effective enough to handle the attacks
of those types above.

We're talking straight pipe vs. pipe DoS options. I'm not aware of any
"legitimate" botnets for this kind of load testing or service providers
which offer similar services so I was hoping to get some ideas/options.



On Mon, 2008-07-14 at 17:24 -0400, Jon Kibler wrote:
Erin Carroll wrote:
Pen-testers,

There have been times when, during the course of a pen-test for a
client, a request is made for DoS/DDoS attacks against external 
systems
& services. While there are resource exhaustion & other attack methods
for certain services/systems, let's assume that Smurf-like attacks
aren't viable. I'm curious for ideas or methods to simulate straight
bandwidth DDoS attacks if the client pipe(s) are larger than your
available pipe(s).

It's not like we all have huge botnets in our back pocket... Has 
anyone
faced this situation before and if so, how did you manage?


Hi,

What services (e.g., IIS x.x, BIND v.e.r)?

What network infrastructure devices (e.g., Cisco xxxx w/ IOS yy.zz)?

What O/Ses / versions?

There are a number of protocol and device specific attacks where a
single to a few hosts with not much bandwidth can successful DoS a
system on a much larger pipe. Attacks are not available for every
environment, but there is usually just enough of a range of equipment
and services on most network to make a DoS attack against something on a
target network possible.

What to look for?
   Fragmentation attacks (e.g., jolt)
   Amplification attacks (e.g., DNS: request a VERY large TXT record)
   Protocol attacks (e.g., LAND)
   Application attacks (e.g., SQL Injection 'shutdown with nowait')

Where to look?
   PacketStorm
   Milw0rm

Just some starters. Give some specifics and I can be more specific.

Hope this helps!

Jon Kibler


Erin,

Okay, let's look at some options within the parameters you just provided.

First, get a *nix hosted server on a very fat pipe -- say an OC48. A /27
netblock would also be a nice addition. You can get one with huge
bandwidth allocations for under $500 / mo. Use this as a basis for other
attacks, such as:
   a) A mail server that uses spf could be attacked by creating HUGE spf
records. Then simply create a script that floods SMTP requests that
would require the retrieval of the spf records. Using a bunch of domains
housed on your fat pipe, you could easily swamp the inbound pipe.

   b) An anonymous ftp server (or, a real ftp server with an account you
have cracked). Flood the server with requests to send/receive huge files.

   c) Dictionary or brute force attacks against mail clients.

   d) Protocol flood, such as ICMP 0/0 with SIP == DIP in both IP header
and payload. (An ICMP LAND attack that also starves bandwidth.) Use a
few thousand hping processes (make sure you don't exceed your kernel's
process limit), each slamming out packets at the maximum rate, such as:
        for i in $(seq 16382)
        do
           hping -i u1 -c 999999999 -q ...
        done

    e) Find a web application that has lame authentication. Then create
multiple data streams, each trying to brute force a user of that
application -- legit user or not. For example, try to BF Citrix
web-based login or client email services (pop or imap). This has three
possible DoS abilities:
        - Lockout of legit users
        - Resource starvation on the application server
        - Bandwidth starvation

   f) Attack a misconfigured name server -- one that allows public
recursion.
        - Set up a bunch of domains w/ default TTL = 1.
        - Create NS records that point to different virtual IPs on your fat
pipe server.
        - Create very large TXT records.
        - Flood the server with requests for those TXT records, but forge the
source IP to be something on the client's network.

   g) Use SQL Injection attacks to:
        - Flood the server with complex queries.
        - Execute stored procedures to shut down the server.

   h) Attack a client and use that to leapfrog to a critical server.
        - Whack a privileged user. For example, if you know that they have
installed an old version of QuickTime, send them one of the Metasploit
QuickTime images embedded in their email, so when they open it, it
starts the vulnerable application, giving you control of their computer.
        - Use this system and the user's privilege to jump to a critical server
and shut it down. (Or, use psshutdown)

   i) Oh, I almost forgot the obvious: Use the Nessus 'DoS' ability on
any exposed vulnerabilities.


Are these these types of ideas you are looking for?

Jon Kibler
- --
Jon R. Kibler
Chief Technical Officer
Advanced Systems Engineering Technology, Inc.
Charleston, SC  USA
o: 843-849-8214
c: 843-224-2494
s: 843-564-4224

My PGP Fingerprint is:
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