Skip to content

Commit

Permalink
change to 3.19 EP2 waf configuration workflow (#1323)
Browse files Browse the repository at this point in the history
  • Loading branch information
@electricjesus
electricjesus authored Mar 8, 2024
1 parent e83eb7c commit 0195e2e
Showing 1 changed file with 126 additions and 87 deletions.
213 changes: 126 additions & 87 deletions calico-enterprise/threat/web-application-firewall.mdx
View file
Original file line number Diff line number Diff line change
Expand Up @@ -25,8 +25,8 @@ Historically, web application firewalls (WAFs) were deployed at the edge of your
### About {{prodname}} WAF

WAF is deployed in your cluster along with Envoy DaemonSet. {{prodname}} proxies selected service traffic through Envoy, checking HTTP requests using the industry-standard
[ModSecurity](https://owasp.org/www-project-modsecurity-core-rule-set/) with OWASP Core Rule Set v3.3.5 modified for kubernetes workloads.
<!--To review the rules deployed with the WAF, see [Ruleset files](https://github.com/tigera/operator/tree/master/pkg/render/applicationlayer/embed/coreruleset/rules).-->
[ModSecurity](https://owasp.org/www-project-modsecurity-core-rule-set/) with OWASP Core Rule Set `v4.0.0-rc2` with some modifications for Kubernetes workloads.


You simply enable WAF in Manager UI, and determine the services that you want to enable for WAF protection. By default WAF is set to `DetectionOnly` so no traffic will be denied until you are ready to turn on blocking mode.

Expand All @@ -36,7 +36,7 @@ Every request that WAF finds an issue with, will result in a Security Event bein

If you configure WAF in blocking mode, WAF will use something called [anomaly scoring mode](https://coreruleset.org/docs/concepts/anomaly_scoring/) to determine if a request is allowed with `200 OK` or denied `403 Forbidden`.

This works by matching a single HTTP request against all the configured WAF rules. Each rule has a score and WAF adds all the matched rule scores together, and compares it to the overall anomaly threshold score (100 by default). If the score is under the threshold the request is allowed and if the score is over the threshold the request is denied. Our WAF starts in detection mode only and with a high default scoring threshold so is safe to turn on and then [fine-tune the WAF](#fine-tuning-your-waf) for your specific needs in your cluster.
This works by matching a single HTTP request against all the configured WAF rules. Each rule has a score and WAF adds all the matched rule scores together, and compares it to the overall anomaly threshold score (100 by default). If the score is under the threshold the request is allowed and if the score is over the threshold the request is denied. Our WAF starts in detection mode only and with a high default scoring threshold so is safe to turn on and then [fine-tune the WAF](#manage-your-waf) for your specific needs in your cluster.

## Before you begin

Expand All @@ -48,7 +48,7 @@ This works by matching a single HTTP request against all the configured WAF rule
WAF cannot be used with:
- Host-networked client pods
- TLS traffic
- [LoadBalancer services](https://kubernetes.io/docs/concepts/services-networking/service/#loadbalancer)
- [LoadBalancer services](https://Kubernetes.io/docs/concepts/services-networking/service/#loadbalancer)
- Egress gateways
- WireGuard on AKS or EKS (unless you apply a specific kernel variable). Contact Support for help.

Expand All @@ -67,7 +67,7 @@ Enabling WAF for certain system services may result in an undesired cluster stat
- `openshift-*`

- Do not enable WAF for system services with the following combination of name and namespaces:
- name: `kubernetes`, namespace: `default`
- name: `Kubernetes`, namespace: `default`
- name: `openshift`, namespace: `default`
- name: `gatekeeper-webhook-service`, namespace: `gatekeeper-system`

Expand All @@ -82,7 +82,7 @@ If you modify the rules, it is recommended to keep your rules in git or similar
- [Enable WAF on your cluster](#enable-waf)
- [Apply WAF to your services](#apply-waf)
- [View WAF events](#view-waf-events)
- [Fine-tuning your WAF](#fine-tuning-your-waf)
- [Manage your WAF](#manage-waf-configuration)
- [Disable WAF feature from your cluster](#disable-waf-feature-from-your-cluster)

### Enable WAF
Expand All @@ -92,7 +92,7 @@ If you don’t have an application to test WAF with or don’t want to use it ri
we recommend that you install the [GoogleCloudPlatform/microservices-demo app](https://github.com/GoogleCloudPlatform/microservices-demo):

```bash
kubectl apply -f https://raw.githubusercontent.com/GoogleCloudPlatform/microservices-demo/release/v0.7.0/release/kubernetes-manifests.yaml
kubectl apply -f https://raw.githubusercontent.com/GoogleCloudPlatform/microservices-demo/release/v0.7.0/release/Kubernetes-manifests.yaml
```

#### Enable WAF using the CLI
Expand Down Expand Up @@ -135,7 +135,7 @@ kubectl annotate svc frontend -n default --overwrite projectcalico.org/l7-loggin
Alternatively, you can use the Manager UI to apply WAF to the `frontend` service.

In this example, we applied WAF to the `frontend` service. This means that every request that goes through the `frontend` service is inspected.
However, the traffic is not blocked because the WAF rule is set to `DetectionOnly` by default. You can adjust rules and start blocking traffic by [fine-tuning your WAF](#fine-tuning-your-waf).
However, the traffic is not blocked because the WAF rule is set to `DetectionOnly` by default. You can adjust rules and start blocking traffic by [fine-tuning your WAF](#manage-your-waf).

In the previous example, we applied WAF to the `frontend` service of the sample application. Here, we are
applying WAF to a service of your own application.
Expand Down Expand Up @@ -164,52 +164,30 @@ Run a simple curl command from any pod inside your cluster targeting a service y
curl http://cartservice/cart?artist=0+div+1+union%23foo*%2F*bar%0D%0Aselect%23foo%0D%0A1%2C2%2Ccurrent_user
```

### Fine-tuning your WAF

#### Manage your rules
The default rule sets work fine for most deployments. However, you can customize them to suit your requirements.
Some common changes are detailed below, for example:

- [Enabling blocking mode](#set-waf-rule-to-block-traffic)
- [Changing the scoring threshold](#change-anomaly-scoring-threshold)
- [Fine-tuning a rule](#change-other-default-settings)
- [Disabling certain rules](#disable-certain-rules)

By default, {{prodname}} ships with Core Rule Set v3.3.5 with the following setup files pre-loaded:

- [tigera.conf](https://github.com/tigera/operator/blob/master/pkg/render/applicationlayer/embed/coreruleset/tigera.conf)
### Manage WAF configuration

There are two ways to edit your rules.
1. Edit the configmap directly using kubectl. The config map combines all the rule files together, so you will need to know how to search and find the exact place in the configmap that you want to update.
Reviewing the default rule set config:

2. If you want to modify the rules in any meaningful way, it is recommended that you download the files locally and modify before replacing the configmap. In OWASP, it is recommended you disable rules or change configuration by modifying a set of specific metadata files and exclusion files, and not modify any of the main rule files directly. You can, of course, decide to replace the rule set entirely with your own set of custom rules. This is completely fine once the rules are written in the same SecRule syntax understood by ModSecurity. We recommend you keep a version of your rule files safe in version control like git.

To download and modify the rule files:
```bash
Include @coraza.conf-recommended
Include @crs-setup.conf.example
Include @owasp_crs/*.conf

1. Clone our operator code which contains the ConfigMap source.
SecRuleEngine DetectionOnly
```

```bash
git clone --depth=1 https://github.com/tigera/operator
cd operator
```
2. Change directory into the actual modsec rule set files we use.
The configuration file starts with importing the appropriate rule set config. We use Coraza WAF's recommended [Core Rule Set setup](https://coraza.io/docs/tutorials/coreruleset/) files:

```bash
cd pkg/render/applicationlayer/modsec-core-ruleset
```
3. Make the changes you want in the setup, conf or exclusion files and save.
4. Create a ConfigMap.
1. Coraza recommended [configuration](https://github.com/corazawaf/coraza/blob/main/coraza.conf-recommended)
1. The rest of the [coreruleset](https://github.com/coreruleset/coreruleset) files, currently [v4.0.0-rc2](https://github.com/coreruleset/coreruleset/tree/v4.0.0-rc2)

```bash
kubectl create cm --dry-run=client --from-file=. -o yaml -n tigera-operator modsecurity-ruleset > $HOME/my-tigera-waf-ruleset.yaml
```
5. Apply the ConfigMap to your cluster.
These files can be customized if desired. Add all your customizations directly under `tigera.conf`:

```bash
kubectl replace -f $HOME/my-tigera-waf-ruleset.yaml
```
```bash
kubectl edit cm -n tigera-operator modsecurity-ruleset
```

After you do these steps, the `modsecurity-ruleset` ConfigMap will be replaced in the `tigera-operator` namespace,
After editing this ConfigMap successfully, the `modsecurity-ruleset` ConfigMap will be replaced in the `tigera-operator` namespace,
which then triggers a rolling restart of your L7 pods. This means that the HTTP connections going through L7 pods at the time of pod termination will be (RST) reset.

:::note
Expand All @@ -221,8 +199,9 @@ In many scenarios, the default example CRS configuration will be a good enough s
you deploy it to make sure it’s right for your environment.
:::

#### Customization options

#### Set WAF rule to block traffic
##### Set WAF to block traffic
By default WAF will not block a request even if it has matching rule violations. The rule engine is set to `DetectionOnly`. You can configure to block traffic instead with an `HTTP 403 Forbidden` response status code when the combined matched rules scores exceed a certain threshold.

1. Edit the configmap:
Expand All @@ -238,58 +217,118 @@ By default WAF will not block a request even if it has matching rule violations.
| On | Denies HTTP traffic. {{prodname}} will log the event in Security Events. | Yes |
| Off | Be cautious about using this option. Traffic is not denied, and there are no events. |No | Yes |

#### Change anomaly scoring threshold

The default scoring threshold is set to 100, a high value that is unlikely to result in blocked requests, even if blocking mode is enabled. A critical rule violation scores 5 by default so a single HTTP request would need many rule violations to pass the default threshold of 100. You are encouraged to fine-tune and lower this threshold value iteratively until you are happy with the requests being allowed and denied for your cluster.
##### Other basic customizations

1. Edit the `crs-setup.conf` file and set `tx.inbound_anomaly_score_threshold` to the value of your choice:
```bash
SecAction \
"id:900110,\
phase:1,\
nolog,\
pass,\
t:none,\
setvar:tx.inbound_anomaly_score_threshold=100,\
setvar:tx.outbound_anomaly_score_threshold=100"
```
For basic customizations, it's best to add it after all the includes in `tigera.conf`. In fact, this is the reason why the `SecRuleEngine` directive and the rest of [our customizations](https://github.com/tigera/operator/blob/master/pkg/render/applicationlayer/embed/coreruleset/tigera.conf#L8-L17) are situated there.
These are the default scoring points for each severity level, applied to each rule individually.
The lower the overall anomaly scoring threshold value is, the more likely it is that traffic will be denied.
An example is adding a sampling mode. For that, the `tigera.conf` will look like this:
| Severity | Score | Description |
| ------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------- |
| Critical | 5 | Mostly generated by the application attack rules (93x and 94x files)
| Error | 4 | Generated mostly from outbound leakage rules (95x files) |
| Warning | 3 | Generated mostly by malicious client rules (91x files) |
| Notice | 2 | Generated mostly by the protocol rules (92x files) |
```bash
# Core Rule Set activation
Include @coraza.conf-recommended
Include @crs-setup.conf.example
Include @owasp_crs/*.conf
SecRuleEngine DetectionOnly
# --- all customizations appear below this line, unless they need a specific loading order like plugins ---
# --- Add sampling mode
# Read about sampling mode here https://coreruleset.org/docs/concepts/sampling_mode/
SecAction "id:900400,\
phase:1,\
pass,\
nolog,\
setvar:tx.sampling_percentage=50"
```
Also you can disable certain rules here:
```bash
# --- disable 'Request content type is not allowed by policy'
SecRuleRemoveById 920420
```
Change anomaly scoring threshold:
```bash
SecAction \
"id:900110,\
phase:1,\
nolog,\
pass,\
t:none,\
setvar:tx.inbound_anomaly_score_threshold=25,\
setvar:tx.outbound_anomaly_score_threshold=20"
```
Or even change rule action parameters or behavior. For example:
```bash
# --- append to more allowed content types to request bodies
SecAction \
"id:900220,\
phase:1,\
nolog,\
pass,\
t:none,\
setvar:'tx.allowed_request_content_type=|application/x-www-form-urlencoded| |multipart/form-data| |multipart/related| |text/xml| |application/xml| |application/soap+xml| |application/json| |application/cloudevents+json| |application/cloudevents-batch+json| |application/grpc|'"
```
##### Using Core Rule Set plugins
Let's go with an example plugin: [Wordpress Rule Exclusions](https://github.com/coreruleset/wordpress-rule-exclusions-plugin/).

Plugin files are the following:

```
wordpress-rule-exclusions-before.conf
wordpress-rule-exclusions-config.conf
```
To include these files properly, structure your work directory like so:
```
tigera.conf
wordpress-rule-exclusions-before.conf
wordpress-rule-exclusions-config.conf
```
#### Change other default settings
and then `tigera.conf` contents should be:
Core Rule Set has several default values and settings that you can fine-tune. Example: Rule 920420 checks the HTTP request Content-Type header against a list of allowed values. You may want to allow traffic through the WAF that has a certain Content-Type that is not allowed by default, e.g. you may have Content-Types in your micro-services workloads that are not allowed by default.
```bash
Include @coraza.conf-recommended
Include /etc/modsecurity-ruleset/wordpress-rule-exclusions-config.conf
Include /etc/modsecurity-ruleset/wordpress-rule-exclusions-before.conf
1. Edit the `crs-setup.conf` file and add a new Content-Type by modifying `id:900220` and appending to the default list named `tx.allowed_request_content_type`
Include @crs-setup.conf.example
Include @owasp_crs/*.conf
```bash
SecAction \
"id:900220,\
phase:1,\
nolog,\
pass,\
t:none,\
setvar:'tx.allowed_request_content_type=|application/x-www-form-urlencoded| |multipart/form-data| |multipart/related| |text/xml| |application/xml| |application/soap+xml| |application/json| |application/cloudevents+json| |application/cloudevents-batch+json| |application/grpc|'"
```
# if your plugin has an -after.conf, include them here
# but wordpress rule exclusions doesn't so we're adding a comment placeholder
# Include /etc/modsecurity-ruleset/wordpress-rule-exclusions-after.conf
#### Disable certain rules
SecRuleEngine DetectionOnly
```

You may want to disable a rule entirely. For example, if you find the allowed Content-Type rule mentioned above too restrictive, you can disable it unconditionally by changing `RESPONSE-999-EXCLUSION-RULES-AFTER-CRS.conf.example` and renaming that file to remove the `.example`:
Then create and apply the configmap:

1. Edit `RESPONSE-999-EXCLUSION-RULES-AFTER-CRS.conf.example` and add a line such as the following, referencing the rule ID you want to disable.
```bash
## create the configuration map itself
kubectl create cm --dry-run=client \
--from-file=tigera.conf \
--from-file=wordpress-rule-exclusions-config.conf \
--from-file=wordpress-rule-exclusions-before.conf \
-n tigera-operator modsecurity-ruleset -o yaml > rule set.configmap.yaml

## replace active configmap
kubectl replace -f rule set.configmap.yaml
```

```bash
SecRuleRemoveById 920420
```
2. Rename `RESPONSE-999-EXCLUSION-RULES-AFTER-CRS.conf.example` to `RESPONSE-999-EXCLUSION-RULES-AFTER-CRS.conf` removing the *.example* in order for ModSecurity to load the file.
Read more about the order of execution for plugins here: https://coreruleset.org/docs/concepts/plugins/

### View WAF events

Expand Down

0 comments on commit 0195e2e

Please sign in to comment.