The Linux kernel is a key part 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 all over the world use day by day like Chromebooks, Android on telephones, vehicles, and TVs, and workloads on Google Cloud. Due to this, now we have closely invested in Linux’s safety – and immediately, we’re saying how we’re constructing on these investments and rising our rewards.
In 2020, we launched an open-source Kubernetes-based Seize-the-Flag (CTF) undertaking referred to as, kCTF. The kCTF Vulnerability Rewards Program (VRP) lets researchers connect with our Google Kubernetes Engine (GKE) situations, and if they’ll hack it, they get a flag, and are probably rewarded. All of GKE and its dependencies are in scope, however each flag caught up to now has been a container breakout via a Linux kernel vulnerability. We’ve discovered that discovering and exploiting heap reminiscence corruption vulnerabilities within the Linux kernel could possibly be made quite a bit tougher. Sadly, safety mitigations are sometimes arduous to quantify, nevertheless, we expect we’ve discovered a means to take action concretely going ahead.
Once we launched kCTF, we hoped to construct a neighborhood of Linux kernel exploitation hackers. This labored nicely and allowed the neighborhood to be taught from a number of members of the safety neighborhood like Markak, starlabs, Crusaders of Rust, d3v17, slipper@pangu, 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 yr, which means we’ll proceed to pay $20,000 – $91,337 USD for vulnerabilities on our lab kCTF deployment to reward the essential work being achieved to know and enhance kernel safety. That is along with our present patch rewards for proactive safety enhancements.
Second, we’re launching new situations with extra rewards to guage the most recent Linux kernel steady picture in addition to new experimental mitigations in a customized kernel we have constructed. Relatively than merely studying in regards to the present state of the steady kernels, the brand new situations will likely be used to ask the neighborhood to assist us consider the worth of each our newest and extra experimental safety mitigations.Â
Right now, we’re beginning with a set of mitigations we consider will make many of the vulnerabilities (9/10 vulns and 10/13 exploits) we acquired this previous yr tougher to take advantage of. For brand new exploits of vulnerabilities submitted which additionally compromise the most recent Linux kernel, we can pay a further $21,000 USD. For these which compromise our customized Linux kernel with our experimental mitigations, the reward will likely be one other $21,000 USD (if they’re clearly bypassing the mitigations we’re testing). This brings the full rewards as much as a most of $133,337 USD. We hope this may permit us to be taught extra about how arduous (or straightforward) 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 protected as we will with the assistance of the safety neighborhood. We hope that, over time, we can make safety mitigations that make exploitation of Linux kernel vulnerabilities as arduous as doable.
