* [Rule Tuning] Windows High Severity - 2
* [Rule Tuning] Windows High Severity - 3
* Revert "[Rule Tuning] Windows High Severity - 3"
This reverts commit 32c8348072ab1629e2a164a3579d866b2682f234.
* [Tuning] AWS Access Token Used from Multiple Addresses
Tuning was triggered by a community member
- fixes wildcard and `Pulumi` typos to exclude common IaC tools
- adds exclusion for ``source.as.organization.name` == "AMAZON-02" and aws.cloudtrail.event_category == "Data"` to exclude the noisy multi-IP traffic coming from Amazon-02 networks performing high-throughput data-plane operations. I didn't exclude this network completely because this network can also indicate user-triggered events that are worth keeping in the alert.
- added additional high noise service providers that may be more indicative of console browsing
- added a field for pairing source.ip & network
- added highlighted fields
* Update rules/integrations/aws/initial_access_iam_session_token_used_from_multiple_addresses.toml
* Update rules/integrations/aws/initial_access_iam_session_token_used_from_multiple_addresses.toml
AWS SNS is a pub/sub style service where users can subscribe to a topic and receive messages published to that topic. Below is a screenshot of the different protocols a user could subscribe with and the various endpoints that could be associated with those protocols.
AWS SNS Email Subscription by Rare User --> AWS SNS Rare Protocol Subscription by User (not a new rule)
- changed the scope of the rule to capture the first time a user/role subscribes to a topic via a particular protocol (ie. email, http, lambda, mobile). Subscribing to an SNS topic via email is a rather normal behavior and it would be normal for each user to subscribe this way "for the first time" making this rule not as valuable as it was intended to be.
- reduced execution window
- added real-world threat references
- added additional MITRE technique and Impact tag
- small edits to IG and Description
- edited highlighted fields
AWS SNS Topic Message Publish by Rare User
- added AWS to name for consistency
-changed new terms fields to use a combination of cloud.account.id and user.name against the topic itself `aws.cloudtrail.resources.arn`. So that instead of simply evaluating the first time a user/role publishes a message to ANY topic, this rule now looks for the first time a user/role publishes a message to a particular topic. We want to make this distinction to capture the case where an identity responsible for publishing to a particular topic A suddenly starts publishing to another topic B, which indicates behavior that should be verified.
- reduced new terms window
- added setup notes as Data events are necessary for capturing the `Publish` API call
- reduced execution window
- added real-world threat references
- added additional MITRE technique and Impact tag
- small edits to IG and Description
- edited highlighted fields
AWS SNS Topic Created by Rare User
- removed the `AssumedRole` and `*-i*` parameters from the query as this narrowed the query to only alert on behavior from EC2 instance roles. We ideally want to evaluate this behavior for all users and roles.
- reduced execution window
- added real-world threat references
- added additional MITRE technique and Impact tag
- small edits to IG and Description
- edited highlighted fields
* [Rule Tuning] AWS S3 Unauthenticated Bucket Access by Rare Source
No query changes as this rule is alerting as expected, however I did change the new terms field to be a combination of an IP address and a particular bucket name. Rather than just alerting for the IP address itself. Perhaps an IP is seen retrieving a doc from a public bucket in the environment (expected behavior) but then it also accesses a file in a bucket meant to be private (unexpected behavior). With new terms only on the IP address we would miss the private bucket access.
- added `tls.client.server_name` to new terms field (bucket name)
- reduced execution window
- removed duplicate IG
- added setup note for turning on data events
- small edits to description and highlighted fields
* Update collection_s3_unauthenticated_bucket_access_by_rare_source.toml
* Update collection_s3_unauthenticated_bucket_access_by_rare_source.toml
* Update collection_s3_unauthenticated_bucket_access_by_rare_source.toml
* Update collection_s3_unauthenticated_bucket_access_by_rare_source.toml
* [Rule Tunings] AWS DynamoDB new terms Rules
### AWS DynamoDB Scan by Unusual User
- changed new terms field to use cloud.account.id and user.name combination to account for roles and users
- reduced execution window
- reduced history window
- small edits to description, IG and highlighted fields
### AWS DynamoDB Table Exported to S3
- removed inaccurate setup notes
- reduced history window
- small edits to description and highlighted fields
* Apply suggestions from code review
This rule is performing as expected and low noise in telemetry so no changes to query
- added investigation fields
- small edits to description and IG
- added a reference from Unit42 showing real world threat case
- reduced execution window
* [Rule Tuning] SSM Session Started to EC2 Instance
Role/role session noise seen in telemetry due to new fields term using `aws.cloudtrail.user_identity.arn`, which is unique for each role session and does not isolate the role itself.
- new fields term change to `cloud.account.id` and `user.name` combination to account for both IAMUsers and Roles across multiple accounts.
- added AWS to the rule name
- reduced execution window
- small edits to description and IG
- added reference from IG to Reference section
* adding highlighted fields
* added EC2 tag
* Update lateral_movement_aws_ssm_start_session_to_ec2_instance.toml
* Apply suggestions from code review
* [Rule Tunings] AWS Route Table Created / AWS EC2 Route Table Modified or Deleted
AWS Route Table Created
- turned this into a new_terms rule to reduce noise and be more indicative of potential malicious behavior. Used `cloud.account.id`, `user.name` combination to account for both roles and users doing this behavior for the first time.
- changed execution interval
- changed the name to add EC2
- slight adjustments to IG and description
- fixed tagging error
- added investigation fields
AWS EC2 Route Table Modified or Deleted
- replaced new terms field to `cloud.account.id`, `user.name` combination to account for both roles and users doing this behavior for the first time.
- removed the exclusions from this rule. These exclusions, while meant to reduce noise caused by automation tools, actually just provide an easy bypass. A user can simply use CloudFormation to perform the exact same behaviors and avoid detection. I've shown this in the screenshot below, I ran a nearly identical script, one with and one without using CloudFormation. While `source.address` is `cloudformation.amazonaws.com` the behavior was still performed by an IAMUser and should still be evaluated. The fact that this is a new terms rule will reduce the risk of noise due to automation using these tools.
- changed execution interval
- slight adjustments to IG and description
- added investigation fields
* Update persistence_route_table_created.toml
* Update rules/integrations/aws/persistence_ec2_route_table_modified_or_deleted.toml
- query change : I chose to replace `aws.cloudtrail.user_identity.arn` with `user.id` and a more accurate wildcard pattern. This will reduce the chances of this rule triggering for role sessions outside of those started by EC2 instances. The wildcard pattern looks for a role session name that starts with `i-` this is because when an EC2 instance operates using it's attached Role (instance profile), the session name attached to that role name is the instance id (`i-......`). The `user.id` field appends this session name to the role name via a standard pattern `:[session_name]`, making it a more reliable field to use in this case.
- small edits to description and IG
- reduced execution window
- reduced history window
- edited highlighted fields
Note: the new_terms field here remains `aws.cloudtrail.user_identity.arn` because we are only interested in assumed roles, and even more particular, only those used by an EC2 instance. This means we want to evaluate each individual instance's behavior rather than the broader behavior of the role itself. The arn field will capture each instance id (session name) alongside the role itself.
Ruben Groenewoud