Posted by Maddie Stone, Google Project Zero

This blog post is an overview of a talk, “ 0-day In-the-Wild Exploitation in 2022…so far”, that I gave at the FIRST conference in June 2022. The slides are available here.

For the last three years, we’ve published annual year-in-review reports of 0-days found exploited in the wild. The most recent of these reports is the 2021 Year in Review report, which we published just a few months ago in April. While we plan to stick with that annual cadence, we’re publishing a little bonus report today looking at the in-the-wild 0-days detected and disclosed in the first half of 2022.        

As of June 15, 2022, there have been 18 0-days detected and disclosed as exploited in-the-wild in 2022. When we analyzed those 0-days, we found that at least nine of the 0-days are variants of previously patched vulnerabilities. At least half of the 0-days we’ve seen in the first six months of 2022 could have been prevented with more comprehensive patching and regression tests. On top of that, four of the 2022 0-days are variants of 2021 in-the-wild 0-days. Just 12 months from the original in-the-wild 0-day being patched, attackers came back with a variant of the original bug.  

So, what does this mean?

When people think of 0-day exploits, they often think that these exploits are so technologically advanced that there’s no hope to catch and prevent them. The data paints a different picture. At least half of the 0-days we’ve seen so far this year are closely related to bugs we’ve seen before. Our conclusion and findings in the 2020 year-in-review report were very similar.

Many of the 2022 in-the-wild 0-days are due to the previous vulnerability not being fully patched. In the case of the Windows win32k and the Chromium property access interceptor bugs, the execution flow that the proof-of-concept exploits took were patched, but the root cause issue was not addressed: attackers were able to come back and trigger the original vulnerability through a different path. And in the case of the WebKit and Windows PetitPotam issues, the original vulnerability had previously been patched, but at some point regressed so that attackers could exploit the same vulnerability again. In the iOS IOMobileFrameBuffer bug, a buffer overflow was addressed by checking that a size was less than a certain number, but it didn’t check a minimum bound on that size. For more detailed explanations of three of the 0-days and how they relate to their variants, please see the slides from the talk.

When 0-day exploits are detected in-the-wild, it’s the failure case for an attacker. It’s a gift for us security defenders to learn as much as we can and take actions to ensure that that vector can’t be used again. The goal is to force attackers to start from scratch each time we detect one of their exploits: they’re forced to discover a whole new vulnerability, they have to invest the time in learning and analyzing a new attack surface, they must develop a brand new exploitation method. To do that effectively, we need correct and comprehensive fixes.

This is not to minimize the challenges faced by security teams responsible for responding to vulnerability reports. As we said in our 2020 year in review report:

Being able to correctly and comprehensively patch isn't just flicking a switch: it requires investment, prioritization, and planning. It also requires developing a patching process that balances both protecting users quickly and ensuring it is comprehensive, which can at times be in tension. While we expect that none of this will come as a surprise to security teams in an organization, this analysis is a good reminder that there is still more work to be done.

Exactly what investments are likely required depends on each unique situation, but we see some common themes around staffing/resourcing, incentive structures, process maturity, automation/testing, release cadence, and partnerships.

Practically, some of the following efforts can help ensure bugs are correctly and comprehensively fixed. Project Zero plans to continue to help with the following efforts, but we hope and encourage platform security teams and other independent security researchers to invest in these types of analyses as well:

• Root cause analysis

Understanding the underlying vulnerability that is being exploited. Also tries to understand how that vulnerability may have been introduced. Performing a root cause analysis can help ensure that a fix is addressing the underlying vulnerability and not just breaking the proof-of-concept. Root cause analysis is generally a pre-requisite for successful variant and patch analysis.

• Variant analysis

Looking for other vulnerabilities similar to the reported vulnerability. This can involve looking for the same bug pattern elsewhere, more thoroughly auditing the component that contained the vulnerability, modifying fuzzers to understand why they didn’t find the vulnerability previously, etc. Most researchers find more than one vulnerability at the same time. By finding and fixing the related variants, attackers are not able to simply “plug and play” with a new vulnerability once the original is patched.

• Patch analysis

Analyzing the proposed (or released) patch for completeness compared to the root cause vulnerability. I encourage vendors to share how they plan to address the vulnerability with the vulnerability reporter early so the reporter can analyze whether the patch comprehensively addresses the root cause of the vulnerability, alongside the vendor’s own internal analysis.

• Exploit technique analysis

Understanding the primitive gained from the vulnerability and how it’s being used. While it’s generally industry-standard to patch vulnerabilities, mitigating exploit techniques doesn’t happen as frequently. While not every exploit technique will always be able to be mitigated, the hope is that it will become the default rather than the exception. Exploit samples will need to be shared more readily in order for vendors and security researchers to be able to perform exploit technique analysis.

Transparently sharing these analyses helps the industry as a whole as well. We publish our analyses at this repository. We encourage vendors and others to publish theirs as well. This allows developers and security professionals to better understand what the attackers already know about these bugs, which hopefully leads to even better solutions and security overall.