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jar-attachments

kql MEDIUM Azure-Sentinel
EmailAttachmentInfoEmailEvents
aptbackdoorhuntingmicrosoftofficial
This rule was pulled from an open-source repository and enriched with AI. Validate in a test environment before deploying to production.
View original rule at Azure-Sentinel →
Retrieved: 2026-05-23T11:00:00Z · Confidence: medium

Hunt Hypothesis

Adversaries may use Java-based payloads embedded in email attachments to establish remote access and maintain persistence across different operating systems. SOC teams should proactively hunt for this behavior in Azure Sentinel to detect and mitigate Adwind RAT activity that leverages Java attachments for initial compromise.

KQL Query

let mailsHTML = EmailAttachmentInfo
| where FileType startswith "Jar"
| distinct NetworkMessageId;
EmailEvents
| where NetworkMessageId in (mailsHTML) and AttachmentCount > 0

Analytic Rule Definition

id: 3a45afa5-e955-4bff-8876-a42934f3533f
name: jar-attachments
description: |
  This query was originally published in the threat analytics report, Adwind utilizes Java for cross-platform impact.
  Adwind is a remote access tool (RAT) that takes advantage of the cross-platform capabilities of the Java framework. It can check which operating system a target is running and adapt accordingly, allowing it to successfully compromise both Windows and macOS devices.
  The query below must be run in Microsoft Defender XDR. This query detects events where a single Java archive, or JAR file, was attached to an incoming email. Since Adwind is distributed as a JAR file, this can help detect the initial access stage of a Adwind attack. Note that, although the behavior detected by this query is typical of attacks that use Adwind malware, unrelated attacks may use the same or similar techniques. Also note that JAR attachments are not necessarily or even often malware, and that further research will be needed to determine if query results are associated with malicious behavior.
  See Hiding a Java class file for an additional query that detects behavior associated with Adwind attacks.
requiredDataConnectors:
- connectorId: MicrosoftThreatProtection
  dataTypes:
  - EmailAttachmentInfo
  - EmailEvents
tactics:
- Initial access
query: |
  let mailsHTML = EmailAttachmentInfo
  | where FileType startswith "Jar"
  | distinct NetworkMessageId;
  EmailEvents
  | where NetworkMessageId in (mailsHTML) and AttachmentCount > 0

Required Data Sources

Sentinel TableNotes
EmailAttachmentInfoEnsure this data connector is enabled
EmailEventsEnsure this data connector is enabled

MITRE ATT&CK Context

References

False Positive Guidance

Original source: https://github.com/Azure/Azure-Sentinel/blob/main/Hunting Queries/Microsoft 365 Defender/Initial access/jar-attachments.yaml