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Netherlands October 12th, 2017

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OWASP Netherland Wiki
All OWASP NL Events 2017

October 12th, 2017

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Radboud University Nijmegen

   Faculty of Science, Huygensgebouw - room HG00.307
   Heyendaalseweg 135, 6525 AJ Nijmegen 
   Parkeergarage P11 


18:00 - 19:00 Registration & Pizzas
19:00 - 19:15 Welcome & OWASP update
19:15 - 20:00 Playing in the Sandbox: Bypassing Adobe Flash Input Validation by Björn Ruytenberg
20:00 - 20:15 Break
20:15 - 21:00 How to rob a bank by Pieter Ceelen
21:00 - 21:30 Networking


Playing in the Sandbox: Bypassing Adobe Flash Input Validation

Sandboxing is a popular technique used by vendors to minimize damages that applications might potentially inflict on a system. Dictated by so-called sandbox policies, legitimate and malicious code alike are restricted in their trust boundaries, preventing unauthorized actions.

Input validation plays an important role in enforcing sandbox policies. With input validation, context often matters: given some policy set, some input may be allowed, while the same input may be invalid given another. File paths are a notable example. In Adobe Flash Player, the "remote" sandbox prohibits local file system access but enables remote connections, while the "local-with-filesystem" sandbox enables the opposite use case.

While being a seemingly simple input format, validating file paths becomes increasingly complicated when considering the entire picture. With Flash constituting the intermediate glue between operating systems and a range of host environments - web browsers, Microsoft Office, PDF readers - one has a diverse landscape of path schemes to consider. This leads to challenges in proper input validation, and as it turns out, subtle but unforgiving mistakes.

This talk examines two sandbox escape vulnerabilities I have recently found in Adobe Flash.

Tracked as CVE-2016-4271, the first vulnerability details a local sandbox escape through bypassing input validation, enabling to exfiltrate local data and obtain Windows user credentials. The second vulnerability, dubbed CVE-2017-3085, extends the vulnerability to include a remote sandbox escape, showing by extension that Adobe's patch for the first vulnerability incompletely solved the issue. In analyzing these vulnerabilities, we review the underlying causes that rendered them possible: arbitrary definitions of what constitutes "remote" and "local", insufficient input validation schemes, and unmitigated platform-specific vulnerabilities. Finally, in light of recent efforts to deprecate Adobe Flash, we also discuss how Flash will remain important in the short and long term - as an attack vector, and as an object of study.

presentation as PDF

How to rob a bank

We are going to digitally rob a bank. Not for profit, but as a friendly match against the security team of this bank. We believe that only perfect practice makes perfect: by simulating an attack as realistically as possible, an organisation is optimally prepared for real incidents. Expect a very practical presentation about modern hacker techniques combined with lessons learned from security teams in defending against targeted attacks.


Björn Ruytenberg

Björn Ruytenberg is an Information Security student at Eindhoven University of Technology and Radboud University. Being a technology enthusiast, he has graduated in the field of Electrical Engineering, and cum laude in the field of Computer Science. His special interests include hardware and software security, in particular when the case at hand stretches across the former disciplines. Aside from his work as a software developer, he is an active participant in bug bounty programs.

Pieter Ceelen

Pieter’s first ‘hack’ was adjusting the sprites in Space Invaders on his MSX and claiming that the aliens now looked like his little sister. 15 Years later he turned his hobby into profession at KPMG, hacking and advising multinational companies (instead of Space Invaders). In 2016, together with three other experts, Pieter founded Outflank: a company specialised in red teaming and attack simulations. Besides being a very experienced hacker and pentester, Pieter brings years of incident response, forensics and threat intelligence knowledge to the table. This allows him to tune his attacks and use the tools and techniques employed by real attackers in red teaming and attack simulations.