Multiple vulnerabilities in Unbound

Published: 2022-08-16

Risk	Medium
Patch available	YES
Number of vulnerabilities	2
CVE-ID	CVE-2022-30698 CVE-2022-30699
CWE-ID	CWE-341
Exploitation vector	Network
Public exploit	N/A
Vulnerable software	Unbound Server applications / DNS servers
Vendor	NLnet Labs

Security Bulletin

This security bulletin contains information about 2 vulnerabilities.

1) Predictable from Observable State

EUVDB-ID: #VU66548

Risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2022-30698

CWE-ID: CWE-341 - Predictable from Observable State

Exploit availability: No

Description

The vulnerability allows a remote attacker to poison DNS cache.

The vulnerability exists due to the way Unbound handles delegation information expiration event. A remote attacker who controls a rouge DNS server can force the Unbound instance to cache incorrect information about subdomain delegation and permanently poison the DNS cache, e.g. perform the "ghost domain names" attack.

The attack is carried out when Unbound is queried for a subdomain of a rogue domain name. The rogue nameserver returns delegation information for the subdomain that updates Unbound's delegation cache. This action can be repeated before expiry of the delegation information by querying Unbound for a second level subdomain which the rogue nameserver provides new delegation information. Since Unbound is a child-centric resolver, the ever-updating child delegation information can keep a rogue domain name resolvable long after revocation.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Unbound: 1.0.0 - 1.16.1

CPE2.3

External links

https://www.nlnetlabs.nl/downloads/unbound/CVE-2022-30698_CVE-2022-30699.txt
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/5L3ZFWZZFPBIL654BG75RWXUMPFQJ5EC/

Q & A

Can this vulnerability be exploited remotely?

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

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

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

2) Predictable from Observable State

EUVDB-ID: #VU66547

Risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2022-30699

CWE-ID: CWE-341 - Predictable from Observable State

Exploit availability: No

Description

The vulnerability allows a remote attacker to poison DNS cache.

The vulnerability exists due to the way Unbound handles delegation information expiration event. A remote attacker who controls a rouge DNS server can force the Unbound instance to cache incorrect information about domain delegation and permanently poison the DNS cache, e.g. perform the "ghost domain names" attack.

The attack is perform when Unbound is queried for a rogue domain name, which cached delegation information is about to expire. The rogue nameserver delays the response until the cached delegation information expires. Upon receiving the delayed answer containing the delegation information, Unbound overwrites the now expired entries.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Unbound: 1.0.0 - 1.16.1

CPE2.3

External links

Q & A

Can this vulnerability be exploited remotely?

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

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

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