SeaDuke Malware - file 3eb86b7b067c296ef53e4857a74e09f12c2b84b666fc130d1f58aec18bc74b0d

Hunt Hypothesis

The detection identifies potential SeaDuke malware activity through the presence of a specific file hash, indicating an adversary may be executing malicious code to exfiltrate data or establish persistence. SOC teams should proactively hunt for this behavior in Azure Sentinel to detect and mitigate advanced threats before significant data loss or system compromise occurs.

YARA Rule

rule SeaDuke_Sample 
{

    meta:
        description = "SeaDuke Malware - file 3eb86b7b067c296ef53e4857a74e09f12c2b84b666fc130d1f58aec18bc74b0d"
        author = "Florian Roth"
        reference = "http://goo.gl/MJ0c2M"
        date = "2015-07-14"
        score = 70
        hash = "d2e570129a12a47231a1ecb8176fa88a1bf415c51dabd885c513d98b15f75d4e"

    strings:
        $s0 = "bpython27.dll" fullword ascii
        $s1 = "email.header(" fullword ascii /* PEStudio Blacklist: strings */
        $s2 = "LogonUI.exe" fullword wide /* PEStudio Blacklist: strings */
        $s3 = "Crypto.Cipher.AES(" fullword ascii /* PEStudio Blacklist: strings */
        $s4 = "mod is NULL - %s" fullword ascii

    condition:
        uint16(0) == 0x5a4d and filesize < 4000KB 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 5 string patterns in its detection logic.

References

False Positive Guidance

Scenario: Legitimate system update using Windows Update
Filter/Exclusion: Check the process.parent_process field to ensure the parent process is svchost.exe or wuauclt.exe, and verify the file path is within a known system directory like C:\Windows\Temp or C:\Windows\SoftwareDistribution.
Scenario: Scheduled backup job using Veeam Backup & Replication
Filter/Exclusion: Filter by process.name to exclude veeambackup.exe and check the process.command_line for backup-related flags. Also, verify the file path is within a backup directory like C:\VeeamBackup\.
Scenario: Admin task involving PowerShell scripting for log analysis
Filter/Exclusion: Use process.name to exclude powershell.exe and check for known admin scripts or paths like C:\Windows\System32\WindowsPowerShell\v1.0\ in the process.cwd field.
Scenario: Legitimate software installation using Chocolatey
Filter/Exclusion: Filter by process.name to exclude choco.exe and check the process.command_line for installation commands. Verify the file path is within a known package directory like C:\ProgramData\chocolatey\.
Scenario: System monitoring tool like Sysmon generating logs
Filter/Exclusion: Use process.name to exclude sysmon64.exe and check the process.parent_process to ensure it’s a trusted process such as services.exe or explorer.exe.