Microsoft Defender for Cloud Apps
Cloud and workloadsWork with the regular expression engine in Defender for Cloud Apps
In brief
The article now uses clearer terminology, describes regular expressions for content inspection and file policies, and highlights supported syntax, limitations, and examples. Link labels, headings, and metadata were also updated.
What Defender admins need to know
No administrator action is required.
Summaries are generated from the documentation change itself.
Documentation change
View on Microsoft LearnThe comparison below shows only the changed extract. Use the full-page view for complete context.
WorkingWork with the RegExregular expression engine in Defender for Cloud Apps
This article provides instructionsMicrosoft Defender for using RegExCloud Apps supports regular expressions (RegEx) for pattern matching in Defendercontent inspection and file policies. Use the supported RegEx syntax, known limitations, and examples to build effective expressions for Cloud Appsyour policies.
Regular expressions in Defender for Cloud Apps
To test regular expressions, you can use the following websites:
RegexPal regular expression tester - Make sure you select Case insensitive.
Regex101 regular expression tester - Provides detailed analysis of the RegEx.
Limitations of regular expressions in Defender for Cloud Apps
- Disallowed back-references: \<number> or \k<name>
Example expressionsRegular expression examples
The following table gives you example expressions and if they would match or not.
@@ -1,17 +1,17 @@ ----title: Working with the RegEx engine-description: This article provides instructions for using RegEx for pattern matching in Defender for Cloud Apps policies.-ms.date: 01/29/2023+title: Work with the regular expression engine in Defender for Cloud Apps+description: Use regular expressions in Microsoft Defender for Cloud Apps policies to match text patterns, understand syntax limitations, and refine content inspection conditions.+ms.date: 07/03/2026 ms.topic: how-to+ai-usage: ai-assisted+ms.custom: msecd-doc-authoring-1016 ----# Working with the RegEx engine+# Work with the regular expression engine in Defender for Cloud Apps > [!IMPORTANT] > File policies retire on January 6, 2027. To maintain file-based data protection, [migrate to Microsoft Purview DLP or auto-labeling policies](migrate-file-policies-to-purview.md). ---This article provides instructions for using RegEx for pattern matching in Defender for Cloud Apps policies.+Microsoft Defender for Cloud Apps supports regular expressions (RegEx) for pattern matching in content inspection and file policies. Use the supported RegEx syntax, known limitations, and examples to build effective expressions for your policies. ## Regular expressions in Defender for Cloud Apps @@ -21,9 +21,9 @@ The Microsoft Defender for Cloud Apps content inspection policies use RegEx for To test regular expressions, you can use the following websites: -- [https://regexpal.com/](https://www.regexpal.com/) - Make sure you select **Case insensitive**.+- [RegexPal regular expression tester](https://www.regexpal.com/) - Make sure you select **Case insensitive**. -- [https://regex101.com/](https://regex101.com/) - Provides detailed analysis of the RegEx.+- [Regex101 regular expression tester](https://regex101.com/) - Provides detailed analysis of the RegEx. ### Limitations of regular expressions in Defender for Cloud Apps @@ -45,7 +45,8 @@ The following limitations are imposed on custom regular expressions: - Disallowed back-references: \\<number\> or \k\<name> -### Example expressions+<a name="example-expressions"></a>+### Regular expression examples The following table gives you example expressions and if they would match or not.