CVE-2020-25685 | Date: (C)2021-01-21 (M)2023-12-22 |
A flaw was found in dnsmasq before version 2.83. When getting a reply from a forwarded query, dnsmasq checks in forward.c:reply_query(), which is the forwarded query that matches the reply, by only using a weak hash of the query name. Due to the weak hash (CRC32 when dnsmasq is compiled without DNSSEC, SHA-1 when it is) this flaw allows an off-path attacker to find several different domains all having the same hash, substantially reducing the number of attempts they would have to perform to forge a reply and get it accepted by dnsmasq. This is in contrast with RFC5452, which specifies that the query name is one of the attributes of a query that must be used to match a reply. This flaw could be abused to perform a DNS Cache Poisoning attack. If chained with CVE-2020-25684 the attack complexity of a successful attack is reduced. The highest threat from this vulnerability is to data integrity.
CVSS Score and Metrics +CVSS Score and Metrics -CVSS V3 Severity: | CVSS V2 Severity: |
CVSS Score : 3.7 | CVSS Score : 4.3 |
Exploit Score: 2.2 | Exploit Score: 8.6 |
Impact Score: 1.4 | Impact Score: 2.9 |
|
CVSS V3 Metrics: | CVSS V2 Metrics: |
Attack Vector: NETWORK | Access Vector: NETWORK |
Attack Complexity: HIGH | Access Complexity: MEDIUM |
Privileges Required: NONE | Authentication: NONE |
User Interaction: NONE | Confidentiality: NONE |
Scope: UNCHANGED | Integrity: PARTIAL |
Confidentiality: NONE | Availability: NONE |
Integrity: LOW | |
Availability: NONE | |
| |