Detects Emdivi Malware | SOC Hunt Feed

Hunt Hypothesis

Emdivi malware is being executed through suspicious process creation and registry modifications that evade standard detection mechanisms. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and contain advanced persistent threats before they cause significant damage.

YARA Rule

rule Emdivi_Gen4
 {

    meta:
        description = "Detects Emdivi Malware"
        author = "Florian Roth @Cyber0ps"
        reference = "https://securelist.com/blog/research/71876/new-activity-of-the-blue-termite-apt/"
        date = "2015-08-20"
        super_rule = 1
        score = 80
        hash1 = "008f4f14cf64dc9d323b6cb5942da4a99979c4c7d750ec1228d8c8285883771e"
        hash2 = "17e646ca2558a65ffe7aa185ba75d5c3a573c041b897355c2721e9a8ca5fee24"
        hash3 = "3553c136b4eba70eec5d80abe44bd7c7c33ab1b65de617dbb7be5025c9cf01f1"
        hash4 = "6a331c4e654dd8ddaa2c69d260aa5f4f76f243df8b5019d62d4db5ae5c965662"
        hash5 = "90d07ea2bb80ed52b007f57d0d9a79430cd50174825c43d5746a16ee4f94ea86"
        hash6 = "a94bf485cebeda8e4b74bbe2c0a0567903a13c36b9bf60fab484a9b55207fe0d"
  
    strings:
        $s1 = ".http_port\", " fullword wide
        $s2 = "UserAgent: " fullword ascii
        $s3 = "AUTH FAILED" fullword ascii
        $s4 = "INVALID FILE PATH" fullword ascii
        $s5 = ".autoconfig_url\", \"" fullword wide
        $s6 = "FAILED TO WRITE FILE" fullword ascii
        $s7 = ".proxy" fullword wide
        $s8 = "AuthType: " fullword ascii
        $s9 = ".no_proxies_on\", \"" fullword wide
  
    condition:
        uint16(0) == 0x5a4d and filesize < 853KB 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 9 string patterns in its detection logic.

References

False Positive Guidance

Scenario: Scheduled system maintenance using Windows Task Scheduler
Filter/Exclusion: Exclude processes initiated by schtasks.exe or with TaskName containing “Maintenance” or “SystemUpdate”
Scenario: Legitimate use of PowerShell for script-based administration
Filter/Exclusion: Exclude processes with ProcessName containing “powershell.exe” and CommandLine containing “script.ps1” or “Invoke-Command”
Scenario: Regular log file rotation performed by Logrotate on Linux systems
Filter/Exclusion: Exclude processes with ProcessName containing “logrotate” or “rsyslog” and CommandLine containing “rotate” or “daily”
Scenario: Windows Event Log cleanup using Event Viewer or wevtutil.exe
Filter/Exclusion: Exclude processes with ProcessName containing “wevtutil.exe” or “eventvwr.exe” and CommandLine containing “clear” or “delete”
Scenario: Database backup job executed by SQL Server Agent
Filter/Exclusion: Exclude processes with ProcessName containing “sqlservr.exe” or “sqlagent.exe” and CommandLine containing “backup” or “restore”