mirror of
https://github.com/splunk/security_content
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d1vious
104 lines
3.8 KiB
Markdown
104 lines
3.8 KiB
Markdown
---
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title: "AWS Lambda UpdateFunctionCode"
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excerpt: "User Execution
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"
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categories:
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- Cloud
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last_modified_at: 2022-02-24
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toc: true
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toc_label: ""
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tags:
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- User Execution
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- Execution
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- Splunk Enterprise
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- Splunk Enterprise Security
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- Splunk Cloud
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---
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[Try in Splunk Security Cloud](https://www.splunk.com/en_us/cyber-security.html){: .btn .btn--success}
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#### Description
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This analytic is designed to detect IAM users attempting to update/modify AWS lambda code via the AWS CLI to gain persistence, futher access into your AWS environment and to facilitate planting backdoors. In this instance, an attacker may upload malicious code/binary to a lambda function which will be executed automatically when the funnction is triggered.
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- **Type**: [Hunting](https://github.com/splunk/security_content/wiki/object-Analytic-Types)
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- **Product**: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
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- **Datamodel**:
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- **Last Updated**: 2022-02-24
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- **Author**: Bhavin Patel, Splunk
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- **ID**: 211b80d3-6340-4345-11ad-212bf3d0d111
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#### [ATT&CK](https://attack.mitre.org/)
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| ID | Technique | Tactic |
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| -------------- | ---------------- |-------------------- |
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| [T1204](https://attack.mitre.org/techniques/T1204/) | User Execution | Execution |
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#### Search
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```
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`cloudtrail` eventSource=lambda.amazonaws.com eventName=UpdateFunctionCode* errorCode = success user_type=IAMUser
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| stats count min(_time) as firstTime max(_time) as lastTime values(requestParameters.functionName) as function_updated by src_ip user_arn user_agent user_type eventName aws_account_id
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|`aws_lambda_updatefunctioncode_filter`
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```
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#### Macros
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The SPL above uses the following Macros:
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* [cloudtrail](https://github.com/splunk/security_content/blob/develop/macros/cloudtrail.yml)
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Note that `aws_lambda_updatefunctioncode_filter` is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
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#### Supported Datasources
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#### Required field
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* _time
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* eventName
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* userAgent
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* errorCode
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#### How To Implement
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You must install Splunk AWS Add on and enable Cloudtrail logs in your AWS Environment.
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#### Known False Positives
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While this search has no known false positives, it is possible that an AWS admin or an autorized IAM user has updated the lambda fuction code legitimately.
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#### Associated Analytic story
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* [Suspicious Cloud User Activities](/stories/suspicious_cloud_user_activities)
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#### Kill Chain Phase
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* Actions on Objectives
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#### RBA
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| Risk Score | Impact | Confidence | Message |
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| ----------- | ----------- |--------------|--------------|
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| 63.0 | 70 | 90 | User $user_arn$ is attempting to update the lambda function code of $function_updated$ from this IP $src_ip$ |
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#### Reference
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* [http://detectioninthe.cloud/execution/modify_lambda_function_code/](http://detectioninthe.cloud/execution/modify_lambda_function_code/)
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* [https://sysdig.com/blog/exploit-mitigate-aws-lambdas-mitre/](https://sysdig.com/blog/exploit-mitigate-aws-lambdas-mitre/)
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#### Test Dataset
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Replay any dataset to Splunk Enterprise by using our [`replay.py`](https://github.com/splunk/attack_data#using-replaypy) tool or the [UI](https://github.com/splunk/attack_data#using-ui).
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Alternatively you can replay a dataset into a [Splunk Attack Range](https://github.com/splunk/attack_range#replay-dumps-into-attack-range-splunk-server)
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* [https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1204/aws_updatelambdafunctioncode/aws_cloudtrail_events.json](https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1204/aws_updatelambdafunctioncode/aws_cloudtrail_events.json)
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[*source*](https://github.com/splunk/security_content/tree/develop/detections/cloud/aws_lambda_updatefunctioncode.yml) \| *version*: **1** |