Automating Kernel Exploitation for Better Flaw Remediation

The explosive disclosure of the Spectre and Meltdown vulnerabilities were like a detonator on the already incendiary field of kernel vulnerabilities this year. Security researchers had previously been ramping up their exploration of kernel bugs, but this year the discoveries have mushroomed considerably.

As CISOs and security personnel seek to mitigate the risk of kernel-level attacks, they're going to need a better way to prioritize vulnerabilities for remediation. A group of researchers set to present at Black Hat USA in a couple of weeks are preparing to offer them a new exploit framework that they say can help security pros do exactly that. 

"Over the past eight months, Syzbot--an automated tool to identify kernel bugs and vulnerabilities--has flagged about 800 kernel bugs," explains Jimmy Su, who leads the JD security research center in Silicon Valley. "However, the Linux kernel community has limited manpower to patch these bugs quickly."

Together with academic researchers Wei Wu and Xinyu Xing of Penn State University, Su will present a new open source framework that they say can help security pros craft "powerful working exploits against arbitrary kernel vulnerabilities in a semi-automated fashion." 

Along with the unveiling of the framework, the trio plans on disclosing a number of working exploits against several kernel vulnerabilities—about half of which had not seen confirmed examples of exploitability in the past. 

"The exploit automation technique is a tool the community can use to quickly assess the exploitability of these bugs, allowing them to prioritize their remediation efforts based on the ease of exploitation," he says. "The goal is to patch kernel bugs with high risks in a timely fashion and reduce the amount of time Linux machines would remain vulnerable."  

While automated exploit generation is hardly a new thing, generating exploits for operating system kernel flaws is notoriously tricky due to complexity and scalability issues, Su and his compatriots say. The new framework they present uses kernel fuzzing and symbolic execution to prod flaws for exploitability under a number of different kernel panic contexts. It provides analysts with three major capabilities; It'll automate identification of system calls needed to exploit the vulnerability, it'll offer automated security mitigation bypassing, and it will automatically generate exploits with different objectives, such as privilege escalation or data leakage.  

Su believes that security teams should generally be leaning on exploit automation as a method for prioritizing vulnerability remediation.

"Every week, an enterprise might handle hundreds or even thousands of software bugs and most organizations don’t have sufficient manpower to sift through and patch these bugs rapidly," he says. "Exploitation automation techniques give an enterprise the ability to identify high-risk bugs and prioritize their remediation efforts accordingly." 

This holds true whether the issues are kernel flaws or not. 

"Though our research demonstrates exploit automation in the context of Linux kernel, our techniques can be generally applied to other daily software," he says. "As such, CISOs can use our technique to prioritize their remediation efforts (and scale) their software security for their daily operation."

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