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CVE-2021-3492 is a vulnerability in shiftfs, an out-of-tree stacking file system used in Ubuntu Linux kernels. The vulnerability arises from improper handling of faults during copy_from_user(), which can result in a double-free or memory not being freed. This flaw can be exploited by an attacker to cause a denial of service (kernel memory exhaustion) or to execute arbitrary code with elevated privileges.
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1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos.
This repository contains a local privilege escalation exploit targeting a double free vulnerability in the SHIFTFS kernel module on Ubuntu 20.10 (5.8.0-xx-generic) 64-bit systems. The exploit is implemented in C (main.c and main_5.4.c) and leverages advanced kernel exploitation techniques, including user namespaces, mount namespaces, BTRFS ioctls, and userfaultfd for precise heap manipulation. The attack surface directory provides scripts for analyzing syscall handlers and kernel tracing, while the exploit directory contains the main exploit code, a Makefile for compilation, and a script to download the necessary kernel symbols from Ubuntu repositories. The exploit achieves arbitrary kernel read/write and function call, ultimately injecting and executing shellcode to gain root privileges. The exploit requires local access and is not a remote exploit. Key fingerprintable endpoints include kernel debug and sysctl file paths. The repository is well-structured for operational exploitation and research.
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