Detects sample mentioned in the Dubnium Report

Hunt Hypothesis

The hypothesis is that the detected sample is associated with the Dubnium Report, indicating potential adversary activity linked to known malicious behavior. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate potential threats early, especially given the report’s association with advanced persistent threats.

YARA Rule

rule Dubnium_Sample_6
{

    meta:
        description = "Detects sample mentioned in the Dubnium Report"
        author = "Florian Roth"
        reference = "https://goo.gl/AW9Cuu"
        date = "2016-06-10"
        super_rule = 1
        hash1 = "5246899b8c74a681e385cbc1dd556f9c73cf55f2a0074c389b3bf823bfc6ce4b"
        hash2 = "5f07b074414513b73e202d7f77ec4bcf048f13dd735c9be3afcf25be818dc8e0"
        hash3 = "839baf85de657b6d6503b6f94054efa8841f667987a9c805eab94a85a859e1ba"

    strings:
        $s1 = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!@#$%^&()`~-_=+[{]{;',." fullword ascii
        $s2 = "e_$0[bW\\RZY\\jb\\ZY[nimiRc[jRZ]" fullword ascii
        $s3 = "f_RIdJ0W9RFb[$Fbc9[k_?Wn" fullword ascii

    condition:
        uint16(0) == 0x5a4d and filesize < 4000KB and all of them
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

• Microsoft Defender for Endpoint — Custom indicators / advanced hunting
• Email Gateway — Attachment scanning
• File Share Monitoring — Periodic scanning of shared drives
• YARA CLI — Manual threat hunting on endpoints

This rule contains 3 string patterns in its detection logic.

References

• https://goo.gl/AW9Cuu
• Source Rule

False Positive Guidance

• Scenario: A system administrator is using PowerShell to run a scheduled job that performs routine system health checks, which includes querying system logs for known issues.
  Filter/Exclusion: Exclude PowerShell scripts that match the signature of known administrative tools or include keywords like "scheduled job", "system health check", or "log analysis".

• Scenario: A Windows Task Scheduler job is configured to run a legitimate script that processes user activity logs, which may contain hashes or strings similar to those in the Dubnium Report.
  Filter/Exclusion: Exclude tasks that are associated with the Task Scheduler service and have a description containing "log processing" or "user activity analysis".

• Scenario: A Windows Event Log collection tool, such as Splunk or Microsoft Log Analytics, is ingesting logs that include hashes or strings from the Dubnium Report as part of normal log data.
  Filter/Exclusion: Exclude events from the Event Log Collector or Log Analytics service, or filter based on the source system or log type (e.g., "EventLog", "Syslog", "Windows Event").

• Scenario: A Windows Update or Group Policy deployment process includes a script that references a hash or string from the Dubnium Report as part of a patch validation check.
  Filter/Exclusion: Exclude processes associated with Windows Update (wuauserv), Group Policy (gpsvc), or scripts with a known update-related context.

• Scenario: A Windows Defender or Microsoft Defender ATP scan is generating alerts due to a false positive match with a benign file or process that is part of the Dubnium Report.
  Filter/Exclusion: Exclude processes running under Windows Defender or Microsoft Defender ATP services, or filter based on the