Vulnerability identifier: #VU10785

Vulnerability risk: Medium

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2018-5734

CWE-ID: CWE-617

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
ISC BIND
Server applications / DNS servers

Vendor: ISC

Description
The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to assertion failure in badcache.c file when processing a DNS request that does not contain all of the expected information. A remote attacker can send a malformed packet to vulnerable version of BIND, trigger the application to select a SERVFAIL rcode instead of a FORMERR rcode and perform a denial of service attack.

Successful exploitation of the vulnerability allows an attacker to trigger denial of service conditions on servers configured to allow recursion with enabled SERVFAIL cache.

Mitigation
Install the latest version from vendor's website.

Vulnerable software versions

ISC BIND: 9.10.5-S1 - 9.10.6-S2

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External links
http://kb.isc.org/article/AA-01562/74/CVE-2018-5734%3A-A-malformed-request-can-trigger-an-assertion...

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

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