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ID

VDE-2021-012

Published

2021-04-26 10:04 (CEST)

Last update

2021-04-26 10:04 (CEST)

Vendor(s)

MB connect line GmbH

Product(s)

Article No° Product Name Affected Version(s)
mbNET HW1 <= 5.1.10
mbNET/mbNET .rokey <= 6.2.5

Summary

Multiple issues have been identified in dnsmasq < 2.83

Vulnerabilities



CVE-2020-25684
3.7
Last Update
July 7, 2021, 10:02 a.m.
Severity
3.7 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N)
Weakness
Improperly Implemented Security Check for Standard (CWE-358)
Summary
A flaw was found in dnsmasq before version 2.83. When getting a reply from a forwarded query, dnsmasq checks in the forward.c:reply_query() if the reply destination address/port is used by the pending forwarded queries. However, it does not use the address/port to retrieve the exact forwarded query, substantially reducing the number of attempts an attacker on the network would have to perform to forge a reply and get it accepted by dnsmasq. This issue contrasts with RFC5452, which specifies a query's attributes that all must be used to match a reply. This flaw allows an attacker to perform a DNS Cache Poisoning attack. If chained with CVE-2020-25685 or CVE-2020-25686, the attack complexity of a successful attack is reduced. The highest threat from this vulnerability is to data integrity.
Details
nvd.nist.gov 
CVE-2020-25685
3.7
Last Update
Nov. 17, 2022, 10:47 a.m.
Severity
3.7 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N)
Weakness
Inadequate Encryption Strength (CWE-326)
Summary
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.
Details
nvd.nist.gov 
CVE-2020-25686
3.7
Last Update
July 7, 2021, 10:02 a.m.
Severity
3.7 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N)
Weakness
Improperly Implemented Security Check for Standard (CWE-358)
Summary
A flaw was found in dnsmasq before version 2.83. When receiving a query, dnsmasq does not check for an existing pending request for the same name and forwards a new request. By default, a maximum of 150 pending queries can be sent to upstream servers, so there can be at most 150 queries for the same name. This flaw allows an off-path attacker on the network to substantially reduce the number of attempts that it would have to perform to forge a reply and have it accepted by dnsmasq. This issue is mentioned in the "Birthday Attacks" section of RFC5452. 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.
Details
nvd.nist.gov 

Impact

Please see the CVE-IDs for details.

Solution

Update to the following versions:

Product Affected Version
mbNET/mbNET .rokey >= 7.0.0
mbNET HW1 >= 5.1.11

Reported by

MB connect line reported this advisory to CERT@VDE.