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Bug 1882014 (CVE-2020-25682)
| Summary: | CVE-2020-25682 dnsmasq: buffer overflow in extract_name() due to missing length check when DNSSEC is enabled | ||
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| Product: | [Other] Security Response | Reporter: | Riccardo Schirone <rschiron> |
| Component: | vulnerability | Assignee: | Red Hat Product Security <security-response-team> |
| Status: | CLOSED ERRATA | QA Contact: | |
| Severity: | high | Docs Contact: | |
| Priority: | high | ||
| Version: | unspecified | CC: | aegorenk, code, dbecker, dns-sig, dougsland, itamar, jima, jjoyce, jschluet, jsvoboda, laine, lhh, lpeer, mburns, pemensik, sclewis, security-response-team, slinaber, veillard |
| Target Milestone: | --- | Keywords: | Security |
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | dnsmasq 2.83 | Doc Type: | If docs needed, set a value |
| Doc Text: |
A flaw was found in dnsmasq. A buffer overflow vulnerability was discovered in the way dnsmasq extract names from DNS packets before validating them with DNSSEC data. An attacker on the network, who can create valid DNS replies, could use this flaw to cause an overflow with arbitrary data in a heap-allocated memory, possibly executing code on the machine. The flaw is in the rfc1035.c:extract_name() function, which writes data to the memory pointed by name assuming MAXDNAME*2 bytes are available in the buffer. However, in some code execution paths, it is possible extract_name() gets passed an offset from the base buffer, thus reducing, in practice, the number of available bytes that can be written in the buffer. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.
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Story Points: | --- |
| Clone Of: | Environment: | ||
| Last Closed: | 2021-01-19 17:59:11 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
| Bug Depends On: | 1896024, 1896026, 1896027, 1896028, 1917782, 1917788 | ||
| Bug Blocks: | |||
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Description
Riccardo Schirone
2020-09-23 15:24:28 UTC
To trigger the flaw, dnsmasq has to be compiled with HAVE_DNSSEC flag and DNSSEC has to be enabled (e.g. with --dnssec option). Moreover, the attacker shall either control a DNS server used in the domain name resolution process or be able to inject packets on the network in such a way to trick dnsmasq into accepting them (e.g. guessing the ID, random port used, etc.). To be involved in the domain name resolution process, an attacker could trick a victim which uses dnsmasq into accessing some resources on a controlled domain, e.g. trick the user to visit a website or open an email. If the dnsmasq service is an Open Resolver (it accepts requests from the whole Internet) or the attacker is on the internal network covered by dnsmasq, the attack can be performed at will by the attacker, without requiring any other user interaction. Acknowledgments: Name: Moshe Kol (JSOF), Shlomi Oberman (JSOF) Statement: This issue does not affect the versions of dnsmasq as shipped with Red Hat Enterprise Linux 5, 6, and 7 as they are not compiled with DNSSEC support. External References: https://www.jsof-tech.com/disclosures/dnspooq/ Mitigation: The only known way to mitigate this flaw is to disable DNSSEC altogether, by removing the `--dnssec` command line option or the `dnssec` option from dnsmasq configuration file. Created dnsmasq tracking bugs for this issue: Affects: fedora-all [bug 1917782] This issue has been addressed in the following products: Red Hat Enterprise Linux 8.1 Extended Update Support Via RHSA-2021:0152 https://access.redhat.com/errata/RHSA-2021:0152 This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2021:0150 https://access.redhat.com/errata/RHSA-2021:0150 Upstream patch: http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=4e96a4be685c9e4445f6ee79ad0b36b9119b502a This issue has been addressed in the following products: Red Hat Enterprise Linux 8.2 Extended Update Support Via RHSA-2021:0151 https://access.redhat.com/errata/RHSA-2021:0151 This bug is now closed. Further updates for individual products will be reflected on the CVE page(s): https://access.redhat.com/security/cve/cve-2020-25682 |