Vulnerability Assessments are not Penetration Tests!

Too often I, as well as many of my co-workers, go into a client and throughout whatever assessment I am working on, general questions come up like, “when’s the last time you’ve had a pen test?” And the client responds, “Ohhh, we do those annually with ‘Some Corporation.’ ” And after looking at ‘Some Corporation’s’ website and seeing what they consider to be a penetration test, I am again disgusted to see that they show up with a vulnerability scanner, run it, validate some findings, and are off to their next client.


Now I know these are some brash comments made toward some random security companies, but let’s be honest here: If you’re going to do something, do it right the first time and provide your client the value of the assessment they paid for. Additionally, give the client what they paid for. If I go to a salesman to buy a sports car and he tries to sell me a Honda Civic, I’m going somewhere else to get what I asked for. On the other side of the coin is the fact that a lot of companies that want a penetration test don’t really understand what it is to begin with. It seems to me that gone are the days of true pen testing when the dreaded “Red Team” shows up to strike real fear into the hearts and minds of Security Practitioners at Fortune 1000 companies.


Any kid in their parent’s basement with savvy computer skills can fire up a Nessus scanner, Web Application Scanners, or Qualys Guard against a network and some of those people can actually interpret the results to make sense out of them. Trust me, everyone on SecureState’s Profiling Team can do that with their eyes closed, but how many security companies out there can actually run a legitimate pen test? I’m not calling anyone out and challenging them, but in all reality, I just want to know how many companies are willing to admit that what they call a “Penetration Test” is actually just a vulnerability assessment? Even worse is the number of companies who perform so called “penetration tests” and truly believe that a vulnerability assessment is the same thing as a pen test.

So let’s all be clear here: a true penetration test is over 85 percent manual and the remaining 15 percent can be a vulnerability scanner to get some other findings in a report in order to provide additional value to the client. And let’s also define manual attacks as to not be ruling out all tools. Using a port scanner is way different than using nCircle, Qualys, or Nessus. Automated scanners like these are the tools that don’t really help a pen test. And just because you use a tool like the Metasploit Framework and many of the tools in Back|Track 4, doesn’t mean you are running a vulnerability scanner. NMAP has the ability to run scripts as well, but again, it doesn’t belong in the Vulnerability Scanner category.

Many times, companies perform Attack and Penetration's due to compliance, or potentially other reasons, which is a bad idea. It gives those companies the opportunity to choose malicious compliance over the desire for truly assessing the security of the entire company. Malicious compliance is a term used when companies do the bare minimum in order to achieve a stamp of approval for whatever standards they are trying to satisfy the needs of. When companies choose to perform pen tests on only their systems affected by compliance, such as PCI or HIPAA systems, they are missing entire networks of systems which aren’t tested. When this happens, companies aren’t getting the true value of what a Pen Test can provide.

SecureState is a trend setting company, and this is where we are going to step in and say, “We Pen Test!” The PCI DSS Council has at least defined what they consider a penetration test. In section 11.3 the Council defines it to be: “vulnerability assessment simply identifies and reports noted vulnerabilities, whereas a penetration test attempts to exploit the vulnerabilities to determine whether unauthorized access or other malicious activity is possible.” Even the EC Council states that, “Penetration testing simulates methods that intruders use to gain unauthorized access to an organization’s networked systems and then compromise them. Penetration testers may use proprietary and/or open source tools to test known technical vulnerabilities in networked systems. Apart from automated techniques, penetration testing involves manual techniques for conducting targeted testing on specific systems to ensure that there are no security flaws that may have gone undetected earlier.”

The SecureState Profiling Team utilizes lower risk vulnerabilities in some systems with additional vulnerabilities in other systems and links them together into larger attacks. By pulling off an attack in this fashion, the Profiling Team utilizes what is called the Vulnerability Linkage Theory in which we can show why it's important to maintain system baselines and other security measures. The Vulnerability Linkage Theory shows how the attack was pulled off by coupling vulnerabilities in many systems to result in the end compromise. For instance, username enumeration from a website, coupled with a brute force attack on the mail system, could allow SecureState to access mail from a company. From here we can email the tech support team and social engineer them into divulging information on how to access the corporate VPN and voila: access to the internal corporate network. There is no way a vulnerability scanner can do that.

Penetration tests zero in to specific systems in order to break in and see what information can be divulged. Pilfering computers and file shares will explain the benefits of Pen Tests by finding the important documents and unencrypted data. Even finding password protected Microsoft Office files can be cracked to release potentially serious data about a company we’re hacking into. Pen Tests can also be used by Security Departments to show why things need to be fixed and get budget to move forward.

There are conflicting views on Pen Tests and Vulnerability Scans. Pen Tests aren’t performed to find vulnerabilities; they are done in order to compromise systems and networks. The main difference between the two is that in a pen test the attackers are actually exploiting vulnerabilities in systems, adding user accounts, and compromising machines across the network. A full or total compromise, which means total control over the entire network, is the end goal of a pen test. Throughout a pen test, the attackers will inevitably generate a list of findings. Many of these findings may be the same as what a vulnerability assessment will also come up with, but there are many vulnerabilities that scanners just can’t find, which leads to the fact that tools can’t think; consultants can. Consultants are able to interpret results and decide on how to use them in order to leverage certain attack vectors against machines and networks.

Don’t get me wrong: I am not discounting the need, want, or value of a vulnerability assessment. These assessments, as well as pen tests, have their place and need. What I am saying is that these assessments need to be better understood in order to know how and when they should be performed. Additionally, there have been companies that run regular vulnerability assessments and the same vulnerabilities keep coming up every single scan. These companies are either overwhelmed with the amount of vulnerabilities present in their networks and don’t know how to fix them, or they don’t see the value or need in fixing them. Penetration tests can enforce the reasoning. In turn, by better understanding what the difference is, the clients will understand what to expect as a final product and won’t be dissatisfied with the results of each test.

Read more!

The big DNS security hole hype exposed

Dan Kaminsky released a little bit ago a joint effort to fix a major and "critical" security flaw with multiple vendors regarding DNS. Dan had stated he was not going to release the vulnerability until his BlackHat speaking in July, but it appears it was already leaked.

DNS Cache Poisoning is nothing new, on July 22, 1999 Hillary Clinton's site was subject to DNS cache poisoning:

http://www.cnn.com/TECH/computing/9907/22/hillary.idg/

It appears that the vulnerability itself is due to predictable TXID's and the lack of port randomization in DNS. Based on TXID inspection (and the blog from Microsoft) it appears that the 4-8 bits are predictable and are able to determine the PRNG state and predict the TXID.

To fix DNS Cache Poisoning, the PRNG algorithm was applied to the TXID or transaction ID's. The vulnerability lies within TXID where the 4-8 bits are predictable allowing the attacker to predict the next TXID. Here's how the attack is suppose to work (hypothetically):

Attacker queries nameserverA for yahoo.com's IP address through DNS. nameserverA doesn't know the IP of yahoo.com. nameserverA goes to the root name servers and says wheres the listings for .com, nameserverA goes to the listings for all .com and looks for the authoritative DNS server for yahoo.com. After that the IP is resolved and you can browse normally to yahoo.com. Where the attack is performed is the request from nameserverA to the authoritative DNS server, when nameserverA sends a request to the root server, the root server sends back a "referral" which tells nameserverA where to go for the .com listings. Contained in this exchange of information is the TXID. It keeps going down the list to various DNS servers, ultimately to the authoritative DNS server.

Our guess at where the attack occurs is the response back from the root server to respond on where yahoo.com's server resides. If an attacker can spoof a valid TXID and say yahoo.com's nameserver is really at ns.badhacker.com and not ns.yahoo.com and ultimately resolves to 1.1.1.1 instead of 2.2.2.2, we can perform cache poisoning of that name server.

So initial speculations that this is bad is pretty accurate and why all the hush was kept to allow all vendors to patch the systems accordingly. Kudos goes out to Dan Kaminsky for taking all of the scrutiny over all of this and allowing vendors time to patch the systems to something that was in fact not just hype but could have major implications if exploited successfully.

I hope all of your DNS servers are patched, a POC should be pretty easy to write off of this.

Special thanks to Microsoft for releasing details about the patch and letting us know what the vulnerability was:

http://blogs.technet.com/swi/archive/2008/04/09/ms08-020-how-predictable-is-the-dns-transaction-id.aspx

Special thanks to John Melvin from SecureState for helping me out on this.

Again this is purely hypothetical, this hasn't been confirmed nor denied.

UPDATE: Update to this post, it appears that it has been confirmed and found by Halvar Flake blog. In addition matasano also discovered it but the site was put up temporarily and taken down when discovered, a mirrored site can be found at: http://beezari.livejournal.com/141796.html. Patch your servers folks!

PATCH: What the patch appears to do, pretty cut and dry, it makes the TXID truly random and randomizes the DNS ports pretty much making this attack useless.

Read more!