A Patch for Postel's Robustness Principle

Sassaman, Len; Patterson, Meredith L.; Bratus, Sergey

doi:10.1109/msp.2012.31

Cited by 10 publications

(7 citation statements)

References 2 publications

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“…Postel's Law, also known as the Robustness Principle, refers to the implementation of protocols and states that one should strictly adhere to the standards when sending, but be liberal in what to accept when receiving [30]. While the benefits of this approach are obvious, numerous discussions have revealed significant issues for the Internet ecosystem caused by following this rule [31], [32]. So far security considerations primarily criticized the increased complexity of liberal implementations, which in turn increases the potential for introducing bugs.…”

Section: Discussionmentioning

confidence: 99%

Attacks on Dynamic Protocol Detection of Open Source Network Security Monitoring Tools

Grashöfer

Titze

Hartenstein

2020

2020 IEEE Conference on Communications and Network Security (CNS)

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Protocol detection is the process of determining the application layer protocol in the context of network security monitoring, which requires a timely and precise decision to enable protocol-specific deep packet inspection. This task has proven to be complex, as isolated characteristics like port numbers are not sufficient to reliably determine the application layer protocol. Hence, more dynamic detection approaches have been developed. In this paper, we analyze the Dynamic Protocol Detection mechanisms employed by popular and widespread open-source network monitoring tools. We show on the example of HTTP that all analyzed detection mechanisms are vulnerable to evasion attacks, which pose a serious threat to real-world monitoring operations. We find that the underlying fundamental problem of protocol disambiguation is not adequately addressed in two of three monitoring systems that we analyzed. To enable adequate operational decisions, this paper highlights the inherent trade-offs within Dynamic Protocol Detection.

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Section: Discussionmentioning

confidence: 99%

Attacks on Dynamic Protocol Detection of Open Source Network Security Monitoring Tools

Grashöfer

Titze

Hartenstein

2020

2020 IEEE Conference on Communications and Network Security (CNS)

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“…As has been noted many times before [34], [35], it may be time to deprecate Postel's Law -'Be conservative in what you send, be liberal in what you accept' -, which was introduced in times when security was less of a concern, and also be conservative in what an implementation accepts.…”

Section: Discussionmentioning

confidence: 99%

Protocol State Machines and Session Languages: Specification, implementation, and Security Flaws

Poll

Ruiter

Schubert

2015

2015 IEEE Security and Privacy Workshops

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Input languages, which describe the set of valid inputs an application has to handle, play a central role in language-theoretic security, in recognition of the fact that overly complex, sloppily specified, or incorrectly implemented input languages are the root cause of many security vulnerabilities.Often an input language not only involves a language of individual messages, but also some protocol with a notion of a session, i.e. a sequence of messages that makes up a dialogue between two parties. This paper takes a closer look at languages for such sessions, when it comes to specification, implementation, and testing -and as a source of insecurity.We show that these 'session' languages are often poorly specified and that errors in implementing them can cause security problems. As a way to improve this situation, we discuss the possibility to automatically infer formal specifications of such languages, in the form of protocol state machines, from implementations by black box testing.

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“…10,11,25,26 While the best-known evasion techniques are from network and transport layers, other protocols can also be used. 10 Evasions exploit the fact that all received traffic is interpreted and that an IPS may interpret it differently from the end system.…”

Section: Evasion Techniquesmentioning

confidence: 99%

“…Attackers may freely craft the network traffic without following the correct protocol semantics. 10,11,25,26 While the best-known evasion techniques are from network and transport layers, other protocols can also be used. Evasions are possible at every OSI layer.…”

Section: Evasion Techniquesmentioning

confidence: 99%

Evaluating intrusion prevention systems with evasions

Särelä

Kyöstilä

Kiravuo

et al. 2017

Int J Communication

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Intrusion prevention systems have become a common security measure in the past 20 years. Their promise is the possibility to prevent known attacks against vulnerable, unpatched devices inside enterprise networks. However, evasion techniques that enable the attacker to evade the eye of the intrusion prevention system are a potential problem for this capability. These techniques take advantage of the robustness principle that has guided designers to create systems that will try to recreate protocol content from any input they receive.In this work, we evaluated the effectiveness of 35 well-known evasions against 9 commercial and 1 free, state-of-the-art, intrusion prevention systems. We conducted 4 experiments with one million attacks against each device. Each system lets a significant amount (0.1%-45%) of attacks pass through unrecognized. Our results show that most existing intrusion prevention systems are vulnerable against evasions.

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A Patch for Postel's Robustness Principle

Cited by 10 publications

References 2 publications

Attacks on Dynamic Protocol Detection of Open Source Network Security Monitoring Tools

Attacks on Dynamic Protocol Detection of Open Source Network Security Monitoring Tools

Protocol State Machines and Session Languages: Specification, implementation, and Security Flaws

Evaluating intrusion prevention systems with evasions

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