#VU15643 Improper access control in Linux kernel - CVE-2018-18281

Vulnerability identifier: #VU15643

Vulnerability risk: Low

CVSSv4.0: 1.1 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2018-18281

CWE-ID: CWE-284

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Linux kernel
Operating systems & Components / Operating system

Vendor: Linux Foundation

Description

The vulnerability allows a local user to bypass certain security restrictions.

The vulnerability exists due to improper access restrictions to memory when performing TLB flushes after dropping pagetable locks with mremap() syscall, A local user can access a physical page of a stale TLB entry after ftruncate() syscall is called to remove entries from the pagetables of a task that is in the middle of mremap() syscall.

Successful exploitation of the vulnerability may allow an attacker to gain access to sensitive information, stored in process memory.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Linux kernel: 4.9.1 - 4.9.134, 4.14 - 4.18.15

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External links
https://packetstormsecurity.com/files/150001/Linux-mremap-TLB-Flush-Too-Late.html
https://www.openwall.com/lists/oss-security/2018/10/29/5
https://bugs.chromium.org/p/project-zero/issues/detail?id=1695
https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.14.78
https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.18.16
https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.9.135
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=eb66ae030829605d61fbef1909ce310e29f78821

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.