Vulnerability identifier: #VU9776

Vulnerability risk: Low

CVSSv3.1: 5.7 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2017-17806

CWE-ID: CWE-121

Exploitation vector: Local

Exploit availability: No

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

Vendor: Linux Foundation

Description
The vulnerability allows a local attacker to cause DoS condition on the target system.

The weakness exists due to the HMAC implementation (crypto/hmac.c) in the Linux kernel does not validate that the underlying cryptographic hash algorithm is unkeyed. A local attacker able to use the AF_ALG-based hash interface (CONFIG_CRYPTO_USER_API_HASH) and the SHA-3 hash algorithm (CONFIG_CRYPTO_SHA3) can execute a specially crafted sequence of system calls that encounter a missing SHA-3 initialization, trigger kernel stack buffer overflow and cause the system to crash.

Successful exploitation of the vulnerability results in denial of service.

Mitigation
Update to version 4.14.8.

Vulnerable software versions

Linux kernel: 4.13.1 - 4.13.16, 4.12.1 - 4.12.14, 4.11.1 - 4.11.12, 4.10.0 - 4.10.17, 4.14 - 4.14.7

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External links
http://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=af3ff8045bbf3e32f1a448...

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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.