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Auto-generated rule - file iamdll.dll

yara CRITICAL Yara-Rules
backdoorcommunity
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 Yara-Rules →
Retrieved: 2026-07-18T23:00:00Z · Confidence: medium

Hunt Hypothesis

This detection targets adversaries attempting to establish persistence or execute malicious code by creating a suspicious iamdll.dll file, which often indicates an attempt to mimic legitimate Identity and Access Management components for credential theft or lateral movement. The SOC team should proactively hunt for this artifact in Azure Sentinel because the critical severity suggests a high-impact compromise where early identification of this specific DLL can prevent unauthorized access before it escalates into a broader identity breach.

YARA Rule

rule iam_iamdll : Toolkit  {
	meta:
		description = "Auto-generated rule - file iamdll.dll"
		author = "Florian Roth"
		reference = "http://www.coresecurity.com/corelabs-research/open-source-tools/pass-hash-toolkit"
		date = "2015-07-10"
		score = 80
		hash = "892de92f71941f7b9e550de00a57767beb7abe1171562e29428b84988cee6602"
	strings:
		$s0 = "LSASRV.DLL" fullword ascii /* score: '21.00' */
		$s1 = "iamdll.dll" fullword ascii /* score: '21.00' */
		$s2 = "ChangeCreds" fullword ascii /* score: '12.00' */
	condition:
		uint16(0) == 0x5a4d and filesize < 115KB and all of them
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

This rule contains 3 string patterns in its detection logic.

References

False Positive Guidance

Here are 5 specific false positive scenarios for the iamdll.dll detection rule in an enterprise environment, including suggested filters and exclusions:

Original source: https://github.com/Yara-Rules/rules/blob/main/malware/TOOLKIT_PassTheHash.yar