The Linux kernel is a key element for the safety of the Web. Google makes use of Linux in nearly the whole lot, from the computer systems our staff use, to the merchandise folks world wide use day by day like Chromebooks, Android on telephones, vehicles, and TVs, and workloads on Google Cloud. Due to this, we have now closely invested in Linux’s safety – and in the present day, we’re saying how we’re constructing on these investments and growing our rewards.
In 2020, we launched an open-source Kubernetes-based Seize-the-Flag (CTF) venture known as, kCTF. The kCTF Vulnerability Rewards Program (VRP) lets researchers hook up with our Google Kubernetes Engine (GKE) situations, and if they will hack it, they get a flag, and are doubtlessly rewarded. All of GKE and its dependencies are in scope, however each flag caught to this point has been a container breakout by way of a Linux kernel vulnerability. We’ve realized that discovering and exploiting heap reminiscence corruption vulnerabilities within the Linux kernel could possibly be made so much more durable. Sadly, safety mitigations are sometimes laborious to quantify, nevertheless, we predict we’ve discovered a manner to take action concretely going ahead.
Once we launched kCTF, we hoped to construct a group of Linux kernel exploitation hackers. This labored nicely and allowed the group to study from a number of members of the safety group like Markak, starlabs, Crusaders of Rust, d3v17, [email protected], valis, kylebot, pqlqpql and Awarau.
Now, we’re making updates to the kCTF program. First, we’re indefinitely extending the elevated reward quantities we introduced earlier this 12 months, which means we’ll proceed to pay $20,000 – $91,337 USD for vulnerabilities on our lab kCTF deployment to reward the necessary work being achieved to know and enhance kernel safety. That is along with our current patch rewards for proactive safety enhancements.
Second, we’re launching new situations with extra rewards to judge the newest Linux kernel secure picture in addition to new experimental mitigations in a customized kernel we have constructed. Moderately than merely studying concerning the present state of the secure kernels, the brand new situations shall be used to ask the group to assist us consider the worth of each our newest and extra experimental safety mitigations.
At present, we’re beginning with a set of mitigations we consider will make many of the vulnerabilities (9/10 vulns and 10/13 exploits) we obtained this previous 12 months tougher to take advantage of. For brand new exploits of vulnerabilities submitted which additionally compromise the newest Linux kernel, we can pay an extra $21,000 USD. For these which compromise our customized Linux kernel with our experimental mitigations, the reward shall be one other $21,000 USD (if they’re clearly bypassing the mitigations we’re testing). This brings the overall rewards as much as a most of $133,337 USD. We hope this can permit us to study extra about how laborious (or simple) it’s to bypass our experimental mitigations.
The mitigations we have constructed try and sort out the next exploit primitives:
With the kCTF VRP program, we’re constructing a pipeline to investigate, experiment, measure and construct safety mitigations to make the Linux kernel as secure as we are able to with the assistance of the safety group. We hope that, over time, we will make safety mitigations that make exploitation of Linux kernel vulnerabilities as laborious as doable.