In etcd before versions 3.3.23 and 3.4.10, the etcd gateway is a simple TCP proxy to allow for basic service discovery and access. However, it is possible to include the gateway address as an endpoint. This results in a denial of service, since the endpoint can become stuck in a loop of requesting itself until there are no more available file descriptors to accept connections on the gateway.
Weakness
The product does not properly control the allocation and maintenance of a limited resource.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Etcd | Redhat | 3.3.0 (including) | 3.3.23 (excluding) |
| Etcd | Redhat | 3.4.0 (including) | 3.4.10 (excluding) |
| Red Hat OpenShift Container Platform 4.8 | RedHat | openshift4/ose-etcd:v4.8.0-202106152230.p0.git.aefa6bf.assembly.stream | * |
| Red Hat OpenStack Platform 16.1 | RedHat | etcd-0:3.3.23-1.el8ost | * |
| Etcd | Ubuntu | bionic | * |
| Etcd | Ubuntu | esm-apps/bionic | * |
| Etcd | Ubuntu | esm-apps/focal | * |
| Etcd | Ubuntu | focal | * |
| Etcd | Ubuntu | groovy | * |
| Etcd | Ubuntu | hirsute | * |
| Etcd | Ubuntu | trusty | * |
| Etcd | Ubuntu | upstream | * |
| Etcd | Ubuntu | xenial | * |
Potential Mitigations
Mitigation of resource exhaustion attacks requires that the target system either:
The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.
The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/147.html
- https://cwe.mitre.org/data/definitions/227.html
- https://cwe.mitre.org/data/definitions/492.html
References
- https://github.com/etcd-io/etcd/security/advisories/GHSA-2xhq-gv6c-p224
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/L6B6R43Y7M3DCHWK3L3UVGE2K6WWECMP/
- https://github.com/etcd-io/etcd/security/advisories/GHSA-2xhq-gv6c-p224
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/L6B6R43Y7M3DCHWK3L3UVGE2K6WWECMP/