GSD-2020-11091
Vulnerability from gsd - Updated: 2023-12-13 01:22Details
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.
Aliases
Aliases
{
"GSD": {
"alias": "CVE-2020-11091",
"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\u0027s 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\u0027s 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.",
"id": "GSD-2020-11091"
},
"gsd": {
"metadata": {
"exploitCode": "unknown",
"remediation": "unknown",
"reportConfidence": "confirmed",
"type": "vulnerability"
},
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"details": "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\u0027s 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\u0027s 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.",
"id": "GSD-2020-11091",
"modified": "2023-12-13T01:22:07.218853Z",
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"TITLE": "Weave Net clusters susceptible to MitM attacks via IPv6 rogue router advertisements"
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"value": "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\u0027s 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\u0027s 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."
}
]
},
"impact": {
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"attackComplexity": "HIGH",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 5.8,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "NONE",
"integrityImpact": "HIGH",
"privilegesRequired": "HIGH",
"scope": "CHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:N/I:H/A:N",
"version": "3.1"
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"cwe_ids": [
"CWE-1035",
"CWE-350",
"CWE-937"
],
"date": "2021-05-27",
"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\u0027s 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\u0027s 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.",
"fixed_versions": [
"2.6.3"
],
"identifier": "CVE-2020-11091",
"identifiers": [
"GHSA-59qg-grp7-5r73",
"CVE-2020-11091"
],
"not_impacted": "All versions starting from 2.6.3",
"package_slug": "go/github.com/weaveworks/weave",
"pubdate": "2021-05-27",
"solution": "Upgrade to version 2.6.3 or above.",
"title": "Reliance on Reverse DNS Resolution for a Security-Critical Action",
"urls": [
"https://github.com/weaveworks/weave/security/advisories/GHSA-59qg-grp7-5r73",
"https://nvd.nist.gov/vuln/detail/CVE-2020-11091",
"https://github.com/weaveworks/weave/commit/15f21f1899060f7716c70a8555a084e836f39a60",
"https://github.com/advisories/GHSA-59qg-grp7-5r73"
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"value": "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\u0027s 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\u0027s 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."
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"impact": {
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"authentication": "SINGLE",
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"vectorString": "AV:N/AC:M/Au:S/C:N/I:P/A:N",
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"scope": "CHANGED",
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"vectorString": "CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:N/I:H/A:N",
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"lastModifiedDate": "2020-06-09T20:02Z",
"publishedDate": "2020-06-03T23:15Z"
}
}
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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