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JavaDropper

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: 2026-07-13T23:00:01Z · Confidence: medium

Hunt Hypothesis

This hypothesis posits that adversaries are utilizing Java-based droppers to stage secondary payloads within the environment by leveraging legitimate Java execution to evade initial scrutiny. The SOC team should proactively hunt for this behavior in Azure Sentinel because early detection of these low-severity staging activities can reveal persistent footholds before they escalate into high-impact lateral movement or data exfiltration events.

YARA Rule

rule JavaDropper : RAT
{
    meta:
	    author = " Kevin Breen <[email protected]>"
	    date = "2015/10"
	    ref = "http://malwareconfig.com/stats/AlienSpy"
	    maltype = "Remote Access Trojan"
	    filetype = "jar"

    strings:
	    $jar = "META-INF/MANIFEST.MF"

	    $a1 = "ePK"
	    $a2 = "kPK"

        $b1 = "config.ini"
        $b2 = "password.ini"

        $c1 = "stub/stub.dll"

        $d1 = "c.dat"

    condition:
        $jar and (all of ($a*) or all of ($b*) or all of ($c*) or all of ($d*))
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

This rule contains 7 string patterns in its detection logic.

False Positive Guidance

Here are 5 specific false positive scenarios for the JavaDropper detection rule in an enterprise environment, along with suggested filters and exclusions:

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