CVE-2020-11091 Detail

Current Description

In Weave Net before version 2.6.3, an attacker able to run a process as root in a container is able to respond to DNS requests from the host and thereby insert themselves as a fake service. In a cluster with an IPv4 internal network, if IPv6 is not totally disabled on the host (via ipv6.disable=1 on the kernel cmdline), it will be either unconfigured or configured on some interfaces, but it's pretty likely that ipv6 forwarding is disabled, ie /proc/sys/net/ipv6/conf//forwarding == 0. Also by default, /proc/sys/net/ipv6/conf//accept_ra == 1. The combination of these 2 sysctls means that the host accepts router advertisements and configure the IPv6 stack using them. By sending rogue router advertisements, an attacker can reconfigure the host to redirect part or all of the IPv6 traffic of the host to the attacker controlled container. Even if there was no IPv6 traffic before, if the DNS returns A (IPv4) and AAAA (IPv6) records, many HTTP libraries will try to connect via IPv6 first then fallback to IPv4, giving an opportunity to the attacker to respond. If by chance you also have on the host a vulnerability like last year's RCE in apt (CVE-2019-3462), you can now escalate to the host. Weave Net version 2.6.3 disables the accept_ra option on the veth devices that it creates.


View Analysis Description

Severity



CVSS 3.x Severity and Metrics:

NIST CVSS score matches with CNA score
CNA:  GitHub, Inc.
Base Score:  5.8 MEDIUM
Vector:  CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:N/I:H/A:N


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Hyperlink Resource
https://github.com/weaveworks/weave/commit/15f21f1899060f7716c70a8555a084e836f39a60 Patch  Third Party Advisory 
https://github.com/weaveworks/weave/security/advisories/GHSA-59qg-grp7-5r73 Third Party Advisory 

Weakness Enumeration

CWE-ID CWE Name Source
CWE-350 Reliance on Reverse DNS Resolution for a Security-Critical Action Provider acceptance level GitHub, Inc.  

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Change History

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Quick Info

CVE Dictionary Entry:
CVE-2020-11091
NVD Published Date:
06/03/2020
NVD Last Modified:
06/09/2020
Source:
GitHub, Inc.