Dca Extractphonenumber

KQL detection rule by reprise99 · MIT

Using regex for searching for MFA phone number changes can be a valuable hunting strategy for understanding user compromise. Regex can be used to look for particular patterns for phone numbers, for instance if your business is in Europe, then USA formatted numbers may be suspicious This query is part of The Definitive Guide to KQL: Using Kusto Query Language for Operations, Defending, and Threat Hunting - https://aka.ms/KQLMSPress and was contributed by Marius F - https://www.linkedin.com/in/mariussagdal/

//Using regex for searching for MFA phone number changes can be a valuable hunting strategy for understanding user compromise. Regex can be used to look for particular patterns for phone numbers, for instance if your business is in Europe, then USA formatted numbers may be suspicious
//This query is part of The Definitive Guide to KQL: Using Kusto Query Language for Operations, Defending, and Threat Hunting - https://aka.ms/KQLMSPress and was contributed by Marius F - https://www.linkedin.com/in/mariussagdal/

//Data connector required for this query - Defender for Cloud Apps

CloudAppEvents 
| where Timestamp >= datetime("Insert date") 
| where ActionType == "Update user." and RawEventData contains "StrongAuthentication" 
| extend target = RawEventData.ObjectId 
| mvexpand ModifiedProperties = parse_json(RawEventData.ModifiedProperties) 
| where ModifiedProperties matches regex @"\+\d{1,3}\s*\d{9,}" 
| mvexpand ModifiedProperties = parse_json(ModifiedProperties) 
| where ModifiedProperties contains "NewValue" and ModifiedProperties matches regex @"\+\d{1,3}\s*\d{9,}" 
| extend PhoneNumber = extract(@"\+\d{1,3}\s*\d{9,}", 0, tostring(ModifiedProperties)) 
| project Timestamp, target, PhoneNumber

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

a7c8fb4d-d1b7-4de7-8a0d-7ef7849d8732

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Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

Rejected pattern present

[[ reason ]]

What does this mean?

Format & documentation suggestions

Not a security issue — this rule is valid and was accepted as-is. These are optional fields/conventions its own format recommends, mainly affecting its quality score and how well it documents itself for other reviewers.

[[ reason ]]

What do these messages mean?

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

[[ currentRule.title ]]

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