(Pwn2Own) Canonical Ubuntu ShiftFS File System Double Free Privilege Escalation Vulnerability
Vulnerability Details
This vulnerability allows local attackers to escalate privileges on affected installations of Canonical Ubuntu. An attacker must first obtain the ability to execute high-privileged code on the target system in order to exploit this vulnerability.
The specific flaw exists within the ShiftFS module. The issue results from the lack of validating the existence of an object prior to performing further free operations on the object. An attacker can leverage this vulnerability to escalate privileges and execute code in the context of the kernel.
Additional Details
Canonical has issued an update to correct this vulnerability. More details can be found at:
https://ubuntu.com/security/CVE-2021-3492
Disclosure Timeline
- 2021-04-19 - Vulnerability reported to vendor
- 2021-04-21 - Coordinated public release of advisory
Credit
Vincent Dehors (@vdehors) from Synacktiv (@Synacktiv)
