Secure Software Development
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Secure Software Development. Risk-Based Security Testing Chapter 7 Rasool Jalili & M.S. Dousti Dept. of Computer Engineering Fall 2010. Risk-Based Security Testing. Security testing.

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Secure software development

Secure Software Development

Risk-Based Security Testing

Chapter 7

Rasool Jalili & M.S. Dousti

Dept. of Computer Engineering

Fall 2010


Secure software development

Risk-Based Security Testing


Secure software development

Security testing

  • Security testing has recently moved beyond the realm of network port scanning to include probing software behavior as a critical aspect of system behavior.

  • Security testing done properly goes much deeper than simple black box probing on the presentation layer

  • and even beyond the functional testing of security mechanism.

  • Testers must carry out a risk-based approach, grounded in both the system's architectural reality and the attacker's mindset.

  • By identifying risks in the system and creating tests driven by those risks, a software security tester can properly focus on areas of code where an attack is likely to succeed.


Secure software development

  • The main difference of security testing and pentest:

    • the level of approach and

    • the timing of the testing itself.

    • Pen-testing happens once software is complete and installed in its operational environment. Also, penetration testing is focused outsidein and is somewhat brief.

    • Security testing can be applied before the software is complete, at the unit level, in a testing environment with stubs and pre-integration.

    • Should start at the feature or component/unit level, prior to system integration.


Secure software development

  • Security unit testing carries the benefit of breaking system security down into a number of discrete parts.

  • Theoretically, if each component is implemented safely and fulfills inter-component design criteria, the greater system should be in reasonable shape.

  • Security testing should continue at the system level and should be directed at properties of the integrated software system.

  • This is precisely where penetration testing meets security testing.

  • Finally, abuse cases developed earlier in the lifecycle should be used to enhance a test plan with adversarial tests based on possible abuse scenarios.

  • Security testing involves as much black hat thinking as white hat thinking.


Secure software development

From OutsideIn to InsideOut

  • Traditional approaches to computer and network security testing focus on network infrastructure, firewalls, and port scanning.

  • This is especially true of network and software penetration testing (application penetration testing).

  • Better penetration testing approaches take architectural risks, code scanning results, and security requirements into account,

  • but still focus on an outsidein perspective.

  • A classic outsidein paradigm focusing on firewall placement.


Secure software development

  • Problem: the perimeter is only apparent at the network/packet level.

  • At the level of software applications, the perimeter has all but disappeared.

  • That's because firewalls have been configured (or mis-configured, depending on your perspective) to allow advanced applications to tunnel right through them.

  • A good example of this phenomenon is the SOAP protocol, which is designed (on purpose) to carry traffic through port 80 for various different applications.

  • In some sense, SOAP is an anti-security device invented by software people.

  • In the brave new world of Service Oriented Architecture (SOA) for applications, we should not be surprised that the firewall is quickly becoming irrelevant.

  • By contrast, in an insideoutapproach to security, whereby software is itself subjected to rigorous risk management and security testing.


Secure software development

What's So Different about Security?

  • Software security is about making software behave in the presence of a malicious attack.

  • Standard software testing literature is only concerned with what happens when software fails, regardless of intent.

  • Software security - Software safety =an intelligent adversary.

  • Most safety-critical systems (and high-assurance systems) posit a white hat world.

  • Fact is, we live in a world with plenty of black hats as well, and we need to address that (head on).

  • Attackers generally don't care whether a vulnerability is due to a flaw or a bug, although bugs tend to be easier to exploit.

  • Design-level vulnerabilities are the hardest defect category to handle.


Secure software development

  • End of today lecture.


Secure software development

Risk Management and Security Testing

  • Different tasks to manage software security risks, such as:

    • Creating security abuse/misuse cases

    • Listing normative security requirements (and security features and functions)

    • Performing architectural risk analysis

    • Building risk-based security test plans

    • Using static analysis tools

    • Performing security tests

    • Performing penetration testing in the final environment

    • Cleaning up security breaches


Secure software development

  • Do not forget: Software security is notsecurity software.

  • So, SWS testing must necessarily involve two diverse approaches:

    • Functional security testing: testing security mechanisms

    • Adversarial security testing: performing risk-based security testing motivated by simulating the attacker's approach

  • Together, these two distinct activities are a mix of white hat (security functionality) and black hat (security attack) philosophies.

  • Wrong belief: liberal application and use of various security features "adding SSL“ to securing an application.

  • Software security practitioners regret the over-reliance on "magic crypto fairy dust“.


Secure software development

How to Approach Security Testing

  • Security testing: determining who should do the testing and what activities they should undertake.

  • Who?

    • Standard testing organizations using a traditional approach  functional security testing.

    • Traditional QA staff? They have more difficulty due to the lack of expertise.

      • Security tests are difficult to design, due to thinking like an attacker.

      • Security tests don't often cause direct security exploit.

    • Bottom line: Risk-based security testing relies more on expertise and security experience (not testing experience).


Secure software development

  • How:

    • Books; helps a lot …

    • White & Black box testing with/ without having access to source.

  • In Black Box testing, malicious input in an effort to break the program;

  • Any testing method can reveal possible software risks and potential exploits.

  • However, One problem with security testing (black or white box) is the lack of it.

  • There is no end-point for software security; even a reasonable security testing regimen is just a start.

  • Unfortunately, security is being sold as a product, and most defensive mechanisms on the market do little to address the heart of the problem, which is bad software.

  • Any testing approach is deeply impacted by software process issues.


Secure software development

Thinking about (Malicious) Input

  • The biggest problems in software security AS software takes input.

  • Trust the input is a critical question that all software builders must consider.

  • From buffer overflow (which involves putting too much input in too small a place) to SQL injection attack and cross-site scripting (XSS) attacks, trusting input is the common root cause.

  • Carefully handling input is dominant to software security.

  • If your program consumes data from "out there," you need to think carefully about who can feed and the stuff your program eats.

  • STOMATH IS THE ROOT OF ALL DESEASES.

  • Attacker toolkits focus plenty of attention on input, with a plenty of fault injection tools, re-players, and the like.

  • By its very nature, penetration testing is focused on input as well

  • If your program accepts input over the network, it needs to be very doubtful of what it is getting.

  • Using a black-list approach (which tries to enumerate all possible bad input) will not work. Instead, software needs to defend its input space with a white-list approach.


Secure software development

Getting Over Input

  • Testing around malicious input is a necessary but not sufficient condition.

  • Security testing needs to focusing on data structures, components, APIs, program state, and so on.

  • In addition to building tests around risks that remain in the system, testers should consider things like:

    • Sockets

    • Pipes

    • The Win32 Registry

    • Files

    • Remote procedure calls (RPCs)

    • Command-line arguments

    • ….

  • Time is a critical issue; two major aspects of time to consider

  • One problem is that most developers are unfamiliar with the effects of multithreading on their systems. That means they often overlook subtle time-based attacks.


Secure software development

  • Unless a security tester thinks like a bad guy (black hat firmly on head), security testing will not be effective.


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