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Detects Mirai Okiru MALW

yara LOW Yara-Rules
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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: 2026-06-24T11:00:00Z · Confidence: medium

Hunt Hypothesis

The hypothesis is that the detection rule identifies potential Mirai Okiru malware activity by monitoring for suspicious network behavior indicative of botnet communication. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate early-stage botnet infections before they cause widespread disruption.

YARA Rule

rule Mirai_Okiru {
	meta:
		description = "Detects Mirai Okiru MALW"
		reference = "https://www.reddit.com/r/LinuxMalware/comments/7p00i3/quick_notes_for_okiru_satori_variant_of_mirai/"
		date = "2018-01-05"

	strings:
		$hexsts01 = { 68 7f 27 70 60 62 73 3c 27 28 65 6e 69 28 65 72 }
		$hexsts02 = { 74 7e 65 68 7f 27 73 61 73 77 3c 27 28 65 6e 69 }
		// noted some Okiru variant doesnt have below function, uncomment to seek specific x86 bins
    // $st07 = "iptables -F\n" fullword nocase wide ascii
    
	condition:
    		all of them
		and is__elf
		and is__Mirai_gen7
		and filesize < 100KB 
}

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

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