From what I can tell, it doesn't seem to be possible to retrieve the OversideHandling property for a WAF rule using a Lambda function. The WAF is returned using client.get_web_acl(...), however the OversizeHandling is stripped out of the rules inside the WAF.
This is problematic because our workflow is that we create a stack in CloudFormation using aws-waf-security-automations, then have a lambda run to make our own customisations to these rules and save them. Because the OversizeHandling is stripped during this process, the end result we are not compliant with the breaking changes being introduced at the end of this month that makes specifying the OversizeHandling mandatory.
I've created a simple proof of concept to demonstrate this:
WAF
Note the OversizeHandling is present in the Body of the SqliMatchStatement
{
"Name": "test-waf2-CloudFrontWAFAutomationsTest-1JLD9J7O1XHCD",
...
"Rules": [
...
{
"Name": "test-waf2-CloudFrontWAFAutomationsTest-1JLD9J7O1XHCDSqlInjectionRule",
"Priority": 20,
"Statement": {
"OrStatement": {
"Statements": [
...
{
"SqliMatchStatement": {
"FieldToMatch": {
"Body": {
"OversizeHandling": "CONTINUE"
}
},
"TextTransformations": [
{
"Priority": 1,
"Type": "URL_DECODE"
},
{
"Priority": 2,
"Type": "HTML_ENTITY_DECODE"
}
],
"SensitivityLevel": "LOW"
}
}
...
Test lambda:
import json
import logging
import boto3
logger = logging.getLogger(__name__)
logger.setLevel(logging.INFO)
client = boto3.client('wafv2')
def lambda_handler(event, context):
web_acl = client.get_web_acl(Name="test-waf2-CloudFrontWAFAutomationsTest-1JLD9J7O1XHCD", Id="b01b9488-6255-443a-b3f5-5f384dc4f0b9", Scope="CLOUDFRONT")
logger.info("Web ACL: %s", web_acl)
Lambda log output
Note there is no OversizeHandling under the Body of the SqliMatchStatement. The SensitivityLevel also appears to be missing.
{
"WebACL":{
"Name":"test-waf2-CloudFrontWAFAutomationsTest-1JLD9J7O1XHCD"
...
"Rules":[
...
{
"Name":"test-waf2-CloudFrontWAFAutomationsTest-1JLD9J7O1XHCDSqlInjectionRule",
"Priority":20,
"Statement":{
"OrStatement":{
"Statements":[
...
{
"SqliMatchStatement":{
"FieldToMatch":{
"Body":{
}
},
"TextTransformations":[
{
"Priority":1,
"Type":"URL_DECODE"
},
{
"Priority":2,
"Type":"HTML_ENTITY_DECODE"
}
]
}
},
Does anyone have any idea why the OversizeHandling is being stripped, or have a suggestion for a workaround? Thank you!
