Making Linux Kernel Exploit Cooking More durable

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Making Linux Kernel Exploit Cooking More durable


The Linux kernel is a key part for the safety of the Web. Google makes use of Linux in nearly all the things, from the computer systems our staff use, to the merchandise individuals world wide use day by day like Chromebooks, Android on telephones, automobiles, 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 asserting how we’re constructing on these investments and growing 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) cases, and if they will 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 realized that discovering and exploiting heap reminiscence corruption vulnerabilities within the Linux kernel may very well be made loads tougher. Sadly, safety mitigations are sometimes onerous to quantify, nevertheless, we expect 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 effectively and allowed the group to study from a number of members of the safety group 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 necessary work being achieved to grasp and enhance kernel safety. That is along with our current patch rewards for proactive safety enhancements.

Second, we’re launching new cases with further rewards to guage the most recent Linux kernel secure picture in addition to new experimental mitigations in a customized kernel we have constructed. Relatively than merely studying concerning the present state of the secure kernels, the brand new cases will probably be used to ask the group to assist us consider the worth of each our newest and extra experimental safety mitigations. 

Immediately, 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 yr harder to use. For brand spanking new exploits of vulnerabilities submitted which additionally compromise the most recent Linux kernel, we pays a further $21,000 USD. For these which compromise our customized Linux kernel with our experimental mitigations, the reward will probably 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 enable us to study extra about how onerous (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 protected as we are able to with the assistance of the safety group. We hope that, over time, we can make safety mitigations that make exploitation of Linux kernel vulnerabilities as onerous as attainable.

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