112 lines
5.1 KiB
Markdown
112 lines
5.1 KiB
Markdown
---
|
|
stage: Manage
|
|
group: Authentication and Authorization
|
|
info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
|
|
type: concepts, reference, howto
|
|
---
|
|
|
|
# Webhooks and insecure internal web services **(FREE SELF)**
|
|
|
|
NOTE:
|
|
On GitLab.com, the [maximum number of webhooks and their size](../user/gitlab_com/index.md#webhooks) per project, and per group, is limited.
|
|
|
|
If you have non-GitLab web services running on your GitLab server or within its
|
|
local network, these may be vulnerable to exploitation via Webhooks.
|
|
|
|
With [Webhooks](../user/project/integrations/webhooks.md), you and your project
|
|
maintainers and owners can set up URLs to be triggered when specific changes
|
|
occur in your projects. Normally, these requests are sent to external web
|
|
services specifically set up for this purpose, that process the request and its
|
|
attached data in some appropriate way.
|
|
|
|
Things get hairy, however, when a Webhook is set up with a URL that doesn't
|
|
point to an external, but to an internal service, that may do something
|
|
completely unintended when the webhook is triggered and the POST request is
|
|
sent.
|
|
|
|
Webhook requests are made by the GitLab server itself and use a single
|
|
(optional) secret token per hook for authorization (instead of a user or
|
|
repository-specific token). As a result, these requests may have broader access than
|
|
intended, including access to everything running on the server hosting the webhook. This
|
|
may include the GitLab server or API itself (for example, `http://localhost:123`).
|
|
Depending on the called webhook, this may also result in network access
|
|
to other servers within that webhook server's local network (for example,
|
|
`http://192.168.1.12:345`), even if these services are otherwise protected
|
|
and inaccessible from the outside world.
|
|
|
|
If a web service does not require authentication, Webhooks can be used to
|
|
trigger destructive commands by getting the GitLab server to make POST requests
|
|
to endpoints like `http://localhost:123/some-resource/delete`.
|
|
|
|
To prevent this type of exploitation from happening, starting with GitLab 10.6,
|
|
all Webhook requests to the current GitLab instance server address and/or in a
|
|
private network are forbidden by default. That means that all requests made
|
|
to `127.0.0.1`, `::1` and `0.0.0.0`, as well as IPv4 `10.0.0.0/8`, `172.16.0.0/12`,
|
|
`192.168.0.0/16` and IPv6 site-local (`ffc0::/10`) addresses aren't allowed.
|
|
|
|
This behavior can be overridden:
|
|
|
|
1. On the top bar, select **Menu > Admin**.
|
|
1. On the left sidebar, select **Settings > Network**.
|
|
1. Expand the **Outbound requests** section:
|
|
|
|
1. Select **Allow requests to the local network from web hooks and services**.
|
|
|
|
NOTE:
|
|
*System hooks* are enabled to make requests to local network by default since they are
|
|
set up by administrators. However, you can turn this off by disabling the
|
|
**Allow requests to the local network from system hooks** option.
|
|
|
|
## Allowlist for local requests
|
|
|
|
> [Introduced](https://gitlab.com/gitlab-org/gitlab-foss/-/issues/44496) in GitLab 12.2
|
|
|
|
You can allow certain domains and IP addresses to be accessible to both *system hooks*
|
|
and *webhooks* even when local requests are not allowed by adding them to the
|
|
allowlist:
|
|
|
|
1. On the top bar, select **Menu > Admin**.
|
|
1. On the left sidebar, select **Settings > Network** (`/admin/application_settings/network`)
|
|
and expand **Outbound requests**:
|
|
|
|
|
|
|
|
The allowed entries can be separated by semicolons, commas or whitespaces
|
|
(including newlines) and be in different formats like hostnames, IP addresses and/or
|
|
IP ranges. IPv6 is supported. Hostnames that contain Unicode characters should
|
|
use [Internationalized Domain Names in Applications](https://www.icann.org/resources/pages/glossary-2014-02-04-en#i)
|
|
(IDNA) encoding.
|
|
|
|
The allowlist can hold a maximum of 1000 entries. Each entry can be a maximum of
|
|
255 characters.
|
|
|
|
You can allow a particular port by specifying it in the allowlist entry.
|
|
For example `127.0.0.1:8080` only allows connections to port 8080 on `127.0.0.1`.
|
|
If no port is mentioned, all ports on that IP/domain are allowed. An IP range
|
|
allows all ports on all IPs in that range.
|
|
|
|
Example:
|
|
|
|
```plaintext
|
|
example.com;gitlab.example.com
|
|
127.0.0.1,1:0:0:0:0:0:0:1
|
|
127.0.0.0/8 1:0:0:0:0:0:0:0/124
|
|
[1:0:0:0:0:0:0:1]:8080
|
|
127.0.0.1:8080
|
|
example.com:8080
|
|
```
|
|
|
|
NOTE:
|
|
Wildcards (`*.example.com`) are not currently supported.
|
|
|
|
<!-- ## Troubleshooting
|
|
|
|
Include any troubleshooting steps that you can foresee. If you know beforehand what issues
|
|
one might have when setting this up, or when something is changed, or on upgrading, it's
|
|
important to describe those, too. Think of things that may go wrong and include them here.
|
|
This is important to minimize requests for support, and to avoid doc comments with
|
|
questions that you know someone might ask.
|
|
|
|
Each scenario can be a third-level heading, e.g. `### Getting error message X`.
|
|
If you have none to add when creating a doc, leave this section in place
|
|
but commented out to help encourage others to add to it in the future. -->
|