EXECryptor 224 StrongbitSoftComplete Development h1 additional

Hunt Hypothesis

This hypothesis targets the presence of StrongbitSoftComplete Development binaries, which are frequently leveraged by adversaries to establish a foothold or execute payloads on Windows systems. Proactively hunting for these specific executables in Azure Sentinel allows the SOC to identify potential low-severity persistence or execution mechanisms before they are chained with more advanced post-exploitation activities.

YARA Rule

rule EXECryptor_224_StrongbitSoftComplete_Development_h1_additional: PEiD
{
    strings:
        $a = { 06 8C C8 8E C0 BE ?? ?? 26 ?? ?? 34 ?? 26 ?? ?? 46 81 ?? ?? ?? 75 ?? 40 B3 ?? B3 ?? F3 }
    condition:
        $a at pe.entry_point

}

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 1 string patterns in its detection logic.

• Source Rule

False Positive Guidance

• Scenario: A developer or DevOps engineer runs the StrongbitSoft Complete Development suite (specifically the EXECryptor component) locally to test encryption/decryption workflows before deploying to the build pipeline. This is a legitimate development task, not an attack.
  • Filter/Exclusion: Exclude processes where the parent process is a known IDE or development tool (e.g., VisualStudio.exe, code.exe, idea64.exe) or where the command line contains arguments typical of development testing (e.g., --test, --local, --debug).
• Scenario: A scheduled maintenance job or CI/CD pipeline step (e.g., in Jenkins, Azure DevOps, or GitHub Actions) executes the EXECryptor binary as part of an automated build or artifact signing process. The process runs under a service account or build agent user.
  • Filter/Exclusion: Exclude executions where the user context matches known CI/CD service accounts (e.g., jenkins-agent, azure-devops-service, github-actions-runner) or where the parent process is a build agent service (e.g., agent.exe, jenkins.exe).
• Scenario: An IT admin or security engineer manually runs the EXECryptor tool from a management workstation to validate a new encryption policy or troubleshoot a specific file encryption issue. The process is launched from a command prompt or PowerShell console.
  • Filter/Exclusion: Exclude executions where the parent process is a standard administrative shell (e.g., cmd.exe, powershell.exe, pwsh.exe) and the user belongs to a privileged group (e.g., Domain Admins, IT-Admins, Security-Engineers).
• Scenario: A legacy application or internal tool that bundles the StrongbitSoft components as a