Pwn2Own 2017

The ZDI Pwn2Own contest celebrated its tenth anniversary this year. Working for Adobe over the past ten years, I have seen a lot of changes in the contest as both an observer and as a vendor triaging the reports.

People often focus on the high level of aspects of who got pwned, how many times, in how many seconds, etc. However, very little of the hyped information is relevant to the actual state of security for the targeted application. There are a lot of factors that determine whether a team chooses to target a platform outside of its relative difficulty.  These can include weighing how to maximize points, the time to prepare, personal skill sets, difficulty in customizing for the target environment, and overall team strategy. ZDI has to publish extremely detailed specs for the targeted environment because even minor device driver differences can kill some exploit chains.

For instance, some of the products that were new additions this year were harder for the teams to add to their target list in time for the competition. On the other hand, it was unsurprising that Tencent and Qihoo 360 both competed against Flash Player since they regularly contribute responsible disclosures to Adobe’s Flash Player and Reader teams. In fact, Tencent was listed in our January Flash Player bulletin and we credited two Flash Player CVEs to the Qihoo 360 Vulcan Team in our March Flash Player security bulletin that went out the day before the contest. On the Reader side, Tencent team members were responsible 19 CVEs in the January release. Therefore, both teams regularly contribute to Adobe’s product security regardless of Pwn2Own.

The vendors don’t make it easy for the competitors. For instance, since the contest occurs after Patch Tuesday, there is always the chance that their bugs will collide with the vendors patch release. For instance, Chrome released 36 patches in March, VMWare had two security updates in March, and Flash Player released seven patches in our March release. In addition, new mitigations sometimes coincide with the contest. Last year, Flash Player switched to Microsoft’s Low Fragmentation Heap and started zeroing memory on free in the release prior to the contest. As a result, one of the Pwn2Own teams from that year did not have time to adjust their attack. This year, Flash Player added more mitigations around heap and metadata isolation in the Patch Tuesday release.

Adobe doesn’t target the mitigations for the contest specifically. These occur as part of our Adobe Secure Product Lifecycle (SPLC) process that continually adds new mitigations. For instance, between Pwn2Own last year and Pwn2Own this year, we added zeroing memory on allocation, running Flash Player in a separate process on Edge, blocking Win32k system calls and font access in Chrome, adding memory protections based on the Microsoft MemProtect concept, and several similar mitigations that are too detailed to include in a simple list. Similarly, Mozilla has been working on instrumenting sandboxing for their browser over the last year. Therefore, this is a contest that does not get any easier as time goes on. If you want to try and sweep all the Pwn2Own categories, then you need a team to do it.

In fact, a lot has changed since 2008 when Flash Player was first hacked in a Pwn2Own contest. The list of mitigations that Flash Player currently has in place includes compiler flags such as GS, SEH, DEP, ASLR and CFG. We have added sandboxing techniques such as job controls, low integrity processes, and app containers for Firefox, Chrome, Safari, and Edge. There have been memory defenses added that include constant folding, constant blinding, random NOP insertion, heap isolation, object length checks, replacing custom heaps, and implementing MemProtect. In addition, the code has gone through rounds of Google fuzzing, Project Zero reviews, and countless contributions from the security community to help eliminate bugs in addition to our internal efforts.

While advanced teams such as Qihoo 360 and Tencent can keep up, that security hardening has hindered others who target Flash Player. For instance, ThreatPost recently wrote an article noting that Trustwave measured a 300% drop in exploit kit activity. While exploit kit activity can be influenced by several factors including law enforcement and market ROI, the CVEs noted in exploit kits are for older versions of Flash Player. As we add mitigations, they not only need new bugs but also new mitigation bypass strategies in order to keep their code working. In addition, ThreatPost noted a recent Qualys report measuring a 40% increase in Flash Player patch adoption which helps to limit the impact of those older bugs. Zero days also have been pushed towards targeting a more limited set of environments.

All of that said, nobody is resting on their laurels. Advanced persistent threats (APTs) will select technology targets based on their mission. If your software is deployed in the environment an APT is targeting, then they will do what is necessary to accomplish their mission. Similarly, in Pwn2Own, we see teams go to extraordinary lengths to accomplish their goals. For instance, Chaitin Security Research Lab chained together six different bugs in order to exploit Safari on MacOS.  Therefore, seeing these creative weaponization techniques inspires us to think of new ways that we can further improve our defenses against determined malicious attackers.

The ZDI team has done a tremendous job improving Pwn2Own each year and adding interesting new levels of gamification. It is amazing to watch how different teams rise to the occasion. Due to the increased difficulty added by vendors each year, even winning a single category becomes a bigger deal with each new year. Thanks to everyone who contributed to making Pwn2Own 2017 a great success.

Peleus Uhley
Principal Scientist

Comments are closed.