---
title: "Suspicious MSBuild Rename"
excerpt: "Masquerading, Trusted Developer Utilities Proxy Execution, Rename System Utilities, MSBuild"
categories:
  - Endpoint
last_modified_at: 2021-01-12
toc: true
toc_label: ""
tags:
  - Masquerading
  - Defense Evasion
  - Trusted Developer Utilities Proxy Execution
  - Defense Evasion
  - Rename System Utilities
  - Defense Evasion
  - MSBuild
  - Defense Evasion
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  - Endpoint
---



[Try in Splunk Security Cloud](https://www.splunk.com/en_us/cyber-security.html){: .btn .btn--success}

#### Description

The following analytic identifies renamed instances of msbuild.exe executing. Msbuild.exe is natively found in C:\Windows\Microsoft.NET\Framework\v4.0.30319 and C:\Windows\Microsoft.NET\Framework64\v4.0.30319. During investigation, identify the code executed and what is executing a renamed instance of MSBuild.

- **Type**: [TTP](https://github.com/splunk/security_content/wiki/Detection-Analytic-Types)
- **Product**: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- **Datamodel**: [Endpoint](https://docs.splunk.com/Documentation/CIM/latest/User/Endpoint)
- **Last Updated**: 2021-01-12
- **Author**: Michael Haag, Splunk
- **ID**: 4006adac-5937-11eb-ae93-0242ac130002


#### [ATT&CK](https://attack.mitre.org/)

| ID             | Technique        |  Tactic             |
| -------------- | ---------------- |-------------------- |
| [T1036](https://attack.mitre.org/techniques/T1036/) | Masquerading | Defense Evasion |

| [T1127](https://attack.mitre.org/techniques/T1127/) | Trusted Developer Utilities Proxy Execution | Defense Evasion |

| [T1036.003](https://attack.mitre.org/techniques/T1036/003/) | Rename System Utilities | Defense Evasion |

| [T1127.001](https://attack.mitre.org/techniques/T1127/001/) | MSBuild | Defense Evasion |

#### Search

```

| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where `process_msbuild` by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.process Processes.process_id Processes.parent_process_id Processes.original_file_name 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `suspicious_msbuild_rename_filter`
```

#### Macros
The SPL above uses the following Macros:
* [process_msbuild](https://github.com/splunk/security_content/blob/develop/macros/process_msbuild.yml)
* [security_content_ctime](https://github.com/splunk/security_content/blob/develop/macros/security_content_ctime.yml)
* [security_content_summariesonly](https://github.com/splunk/security_content/blob/develop/macros/security_content_summariesonly.yml)

Note that `suspicious_msbuild_rename_filter` is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

#### Required field
* _time
* Processes.dest
* Processes.user
* Processes.parent_process_name
* Processes.parent_process
* Processes.original_file_name
* Processes.process_name
* Processes.process
* Processes.process_id
* Processes.parent_process_path
* Processes.process_path
* Processes.parent_process_id


#### How To Implement
To successfully implement this search you need to be ingesting information on process that include the name of the process responsible for the changes from your endpoints into the `Endpoint` datamodel in the `Processes` node. In addition, confirm the latest CIM App 4.20 or higher is installed and the latest TA for the endpoint product.

#### Known False Positives
Although unlikely, some legitimate applications may use a moved copy of msbuild, triggering a false positive.

#### Associated Analytic story
* [Trusted Developer Utilities Proxy Execution MSBuild](/stories/trusted_developer_utilities_proxy_execution_msbuild)
* [Cobalt Strike](/stories/cobalt_strike)
* [Masquerading - Rename System Utilities](/stories/masquerading_-_rename_system_utilities)


#### Kill Chain Phase
* Exploitation



#### RBA

| Risk Score  | Impact      | Confidence   | Message      |
| ----------- | ----------- |--------------|--------------|
| 63.0 | 70 | 90 | Suspicious renamed msbuild.exe binary ran on $dest$ by $user$ |


Note that risk score is calculated base on the following formula: `(Impact * Confidence)/100`



#### Reference

* [https://lolbas-project.github.io/lolbas/Binaries/Msbuild/](https://lolbas-project.github.io/lolbas/Binaries/Msbuild/)
* [https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1127.001/T1127.001.md](https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1127.001/T1127.001.md)
* [https://github.com/infosecn1nja/MaliciousMacroMSBuild/](https://github.com/infosecn1nja/MaliciousMacroMSBuild/)



#### Test Dataset
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).
Alternatively you can replay a dataset into a [Splunk Attack Range](https://github.com/splunk/attack_range#replay-dumps-into-attack-range-splunk-server)

* [https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1127.001/windows-sysmon.log](https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1127.001/windows-sysmon.log)



[*source*](https://github.com/splunk/security_content/tree/develop/detections/endpoint/suspicious_msbuild_rename.yml) \| *version*: **2**