Gaining access using application and operating system attacks

In this excerpt from Chapter 7 of Counter Hack Reloaded: A Step-by-Step Guide to Computer Attacks and Effective Defenses, Second Edition, authors Ed Skoudis and Tom Liston explain how security professionals can use exploit frameworks to their advantage.

Counter Hack Reloaded: A Step-by-Step Guide to Computer Attacks and Effective Defenses, Second Edition

Ed Skoudis & Tom Liston

784 pages; $44.99

Prentice Hall

In this excerpt from Chapter 7 of Counter Hack Reloaded: A Step-by-Step Guide to Computer Attacks and Effective Defenses, Second Edition, authors Ed Skoudis and Tom Liston explain how security professionals can use exploit frameworks to their advantage.


Benefits for the good guys too?

Exploit frameworks aren't just evil. Tools like Metasploit can also help us security professionals to improve our practices as well. One of the most valuable aspects of these tools to infosec pros involves minimizing the glut of false positives from our vulnerability-scanning tools. Chief Information Security Officers (CISOs) and auditors often lament the fact that many of the high-risk findings discovered by a vulnerability scanner turn out to be mere fantasies, an error in the tool that thinks a system is vulnerable when it really isn't. Such false positives sometimes comprise 30 to 50 percent or more of the findings of an assessment. When a CISO turns such an erroneous report over to an operations team of system administrators to fix the nonexistent problems, not only does the operations team waste valuable resources, but the CISO could lose face in light of these false reports. Getting the ops team to do the right thing in tightening and patching systems is difficult enough, and it only gets harder if you are wrong about half of the vulnerability information you send them in this boy-who-cried-wolf situation.

Metasploit can help alleviate this concern. The assessment team first runs a vulnerability scanner and generates a report. Then, for each of the vulnerabilities identified, the team runs an exploit framework like Metasploit to verify the presence of the flaw. The Metasploit framework can give a really high degree of certainty that the vulnerability is present, because it lets the tester gain access to the target machine. Real problems can then be given high priority for fixing. Although this high degree of certainty is invaluable, it's important to note that some exploits inside of the frameworks still could cause a target system or service to crash. Therefore, be careful when running such tools, and make sure the operations team is on standby to restart a service if the exploit does indeed crash it.

In addition to improving the accuracy of security assessments, exploit frameworks can help us check our IDS and IPS tools' functionality. Occasionally, an IDS or IPS might seem especially quiet. Although a given sensor might normally generate a dozen alerts or more per day, sometimes you might have an extremely quiet day, with no alerts coming in over a long span of time. When this happens, many IDS and IPS analysts start to get a little nervous, worrying that their monitoring devices are dead, misconfigured, or simply not accessible on the network. Compounding the concern, we might soon face attacks involving more sophisticated bad guys launching exploits that actually bring down our IDS and IPS tools, in effect rendering our sensor capabilities blind. The most insidious exploits would disable the IDS and IPS detection functionality while putting the system in an endless loop, making them appear to be just fine, yet blind to any actual attacks. To help make sure your IDS and IPS tools are running properly, consider using an exploit framework to fire some sploits at them on a periodic basis, such as once per day. Sure, you could run a vulnerability-scanning tool against a target network to test your detection capabilities, but that would trigger an avalanche of alerts. A single sploit will tell you if your detector is still running properly without driving your analysis team batty.

One of the most common and obvious ways the good guys use exploit frameworks is to enhance their penetration testing activities. With a comprehensive and constantly updated set of exploits and payloads, a penetration tester can focus more on the overall orchestration of an attack and analyzing results instead of spending exorbitant amounts of time researching, reviewing, and tweaking individual exploits. Furthermore, for those penetration testers who devise their own exploit code and payloads, the frameworks offer an excellent development environment. Exploit frameworks don't completely automate penetration test exercises, though. An experienced hand still needs to plan the test, launch various tools including the exploit framework, correlate tool output, analyze results, and iterate to go deeper into the targets. Still, if you perform penetration testing in-house, your team could significantly benefit from these tools, performing more comprehensive tests in less time. If you rely on an external penetration testing company, ask them which of the various exploit frameworks they use, and how they apply them in their testing regimen to improve their attacks and lower costs.

One final benefit offered by exploit frameworks should not be overlooked -- improving management awareness of the importance of good security practices. Most security pros have to work really hard to make sure management understands the security risks our organizations face, emphasizing the need for system hardening, thorough patching, and solid incident response capabilities. Sometimes, management's eyes glaze over hearing for the umpteenth time the importance of these practices. Yet, a single sploit is often worth more than a thousand words. Set up a laboratory demo of one of the exploit frameworks, such as Metasploit. Build a target system that lacks a crucial patch for a given exploit in the framework, and load a sample text file on the target machine with the contents "Please don't steal this important file!" Pick a very reliable exploit to demonstrate. Then, after you've tested your demo to make sure it works, invite management to watch how easy it is for an attacker to use the point-and-click Web interface of Metasploit to compromise the target. Snag a copy of the sensitive file and display it to your observers. When first exposed to these tools, some managers' jaws drop at their power and simplicity. As the scales fall from their eyes, your plea for adequate security resources might now reach a far more receptive audience, thanks to your trusty exploit framework.

More information

  • Download Chapter 7, Gaining access using application and operating system attacks, to learn how to secure your Web applications
This was first published in December 2005

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