Security restrictions bypass in Linux Kernel

1) Improper access control

EUVDB-ID: #VU15643

Risk: Low

CVSSv3.1: 3.9 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2018-18281

CWE-ID: CWE-284 - Improper Access Control

Exploit availability: No

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 - 4.18.15

External links

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

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.