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CVE-2016-4557 is a use-after-free vulnerability in the Linux kernel's eBPF subsystem, specifically in the replace_map_fd_with_map_ptr function in kernel/bpf/verifier.c prior to version 4.5.5. The flaw is due to improper reference counting and double fdput() of file descriptors when handling BPF instructions, leading to a use-after-free condition on struct file objects. This can be exploited by local unprivileged users via crafted BPF instructions to gain root privileges or cause a denial of service. The vulnerability is present when CONFIG_BPF_SYSCALL is enabled and unprivileged BPF is not disabled. The issue was introduced by commit 1be7f75 and fixed by commit 8358b02.
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1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos (1 hidden).
This repository contains a single Metasploit module (modules/exploits/linux/local/bpf_priv_esc.rb) that exploits CVE-2016-4557, a use-after-free vulnerability in the Linux kernel's eBPF subsystem (versions 4.4 < 4.5.5). The exploit enables local privilege escalation to root by abusing improper reference counting of file descriptors. The module uploads and executes exploit binaries and a payload (default: meterpreter reverse shell) on the target. It achieves persistence and privilege escalation by overwriting the first lines of /etc/crontab to schedule the payload for execution as root, which requires manual cleanup. The exploit is weaponized, supporting customizable payloads and automated cleanup routines. The only fingerprintable endpoints are the /etc/crontab file (modified) and the /tmp directory (used for file drops). The module is intended for use on vulnerable Linux systems where the attacker already has local code execution.
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