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Malware or hack tool used by attackers in Operation Cleaver

yara HIGH 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: 2026-05-31T23:00:00Z · Confidence: medium

Hunt Hypothesis

Attackers in Operation Cleaver are using custom malware or hack tools to establish persistence and exfiltrate data from compromised systems. Proactively hunting for this behavior in Azure Sentinel can help identify early-stage compromise and prevent further lateral movement and data theft.

YARA Rule

rule OPCLEAVER_SynFlooder
{

    meta:
        description = "Malware or hack tool used by attackers in Operation Cleaver"
        reference = "http://cylance.com/assets/Cleaver/Cylance_Operation_Cleaver_Report.pdf"
        date = "2014/12/02"
        author = "Cylance Inc."
        score = "70"

    strings:
        $s1 = "Unable to resolve [ %s ]. ErrorCode %d"
        $s2 = "your target’s IP is : %s"
        $s3 = "Raw TCP Socket Created successfully."

    condition:
        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

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