CVE-2021-3490 - Pwning Linux kernel eBPF on Ubuntu machines
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2021-3490 | The eBPF ALU32 bounds tracking for bitwise ops (AND, OR and XOR) in the Linux kernel did not properly update 32-bit bounds, which could be turned into out of bo The eBPF ALU32 bounds tracking for bitwise ops (AND, OR and XOR) in the Linux kernel did not properly update 32-bit bounds, which could be turned into out of bounds reads and writes in the Linux kernel and therefore, arbitrary code execution. This issue was fixed via commit 049c4e13714e ("bpf: Fix alu32 const subreg bound tracking on bitwise operations") (v5.13-rc4) and backported to the stable kernels in v5.12.4, v5.11.21, and v5.10.37. The AND/OR issues were introduced by commit 3f50f132d840 ("bpf: Verifier, do explicit ALU32 bounds tracking") (5.7-rc1) and the XOR variant was introduced by 2921c90d4718 ("bpf:Fix a verifier failure with xor") ( 5.10-rc1). NVD description · AI analysis pending | 7.8 | 27% | PoC |
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Full article276 words · extracted from securityaffairs.com · click to collapse
Researcher published an exploit code for a high-severity privilege escalation flaw (CVE-2021-3490) in Linux kernel eBPF on Ubuntu machines.
The security researcher Manfred Paul of the RedRocket CTF team released the exploit code for a high-severity privilege escalation bug, tracked as CVE-2021-3490, in Linux kernel eBPF (Extended Berkeley Packet Filter). A local attacker could exploit the flaw to escalate privileges on Ubuntu machines.
Extended Berkeley Packet Filter (eBPF) is a kernel technology (starting in Linux 4.x) that allows programs to run without having to change the kernel source code or adding additional modules. It is a sort of lightweight, sandbox virtual machine (VM) inside the Linux kernel, where programmers can run BPF bytecode that takes advantage of specific kernel resources.
Paul reported the bug in May through Trend Micro’s Zero Day Initiative, he demonstrated that user-supplied programs are not properly validated before being executed.
The security researcher Valentina Palmiotti published a blog post that contains technical details about the flaw along with the exploit code that works on fresh installs of both Ubuntu 20.10 and 21.04
So excited to finally release my blog post- Kernel Pwning with eBPF: a Love Story. I cover eBPF, the verifier, debugging, exploitation, mitigations and other cool findings! I do root cause analysis and exploit CVE-2021-3490 for LPE with PoC included. https://t.co/pWt1psHEFa
— chompie (@chompie1337) July 29, 2021
She demonstrates how to exploit the issue to trigger a DoS condition of escalate privileges.
Below is a video PoC for the CVE-2021-3490 vulnerability on Ubuntu 21.04 published by the researcher:
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Text extracted automatically; images, tables and formatting may be missing. Original: https://securityaffairs.com/120688/hacking/cve-2021-3490-linux-kernel-bug.html