DualseXe10

Hunt Hypothesis

This hypothesis targets the presence of the DualseXe10 YARA signature, which indicates a specific low-severity malware or suspicious binary pattern that may represent an initial foothold or a known threat actor tool. Proactively hunting for this indicator in Azure Sentinel allows the SOC team to identify dormant or stealthy infections before they escalate, ensuring early detection of potential compromise vectors that standard high-severity alerts might miss.

YARA Rule

rule DualseXe10
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 81 EC 00 05 00 00 E8 00 00 00 00 5D 81 ED 0E 00 00 00 8D 85 08 03 00 00 89 28 33 FF 8D 85 7D 02 00 00 8D 8D 08 03 00 00 2B C8 8B 9D 58 03 00 00 E8 1C 02 00 00 8D 9D 61 02 00 00 8D B5 7C 02 00 00 46 80 3E 00 74 24 56 FF 95 0A 04 00 00 46 80 3E 00 }

condition:
		$a0 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 uses Visual Studio Code or JetBrains IDEs to compile a C/C++ project, resulting in the creation of a new executable file (*.exe) in the local workspace or build directory.
  • Filter/Exclusion: Exclude files located in common development directories (e.g., C:\Users\<User>\source\, C:\dev\, C:\projects\) or files created by processes associated with known IDEs (e.g., devenv.exe, idea64.exe, code.exe).
• Scenario: An administrator runs a scheduled maintenance job using Task Scheduler or PowerShell that involves downloading a small utility (e.g., a patch installer or a diagnostic tool) from an internal repository and executing it, which may leave a temporary .exe file in the %TEMP% or %LOCALAPPDATA% directory.
  • Filter/Exclusion: Exclude files created by processes such as cmd.exe, powershell.exe, or schtasks.exe if the parent process is a known system service or if the file path contains Temp, tmp, or Local\Temp.
• Scenario: A user installs a portable application (e.g., 7-Zip, WinRAR, or Notepad++) by extracting it to a user-specific folder (e.g., C:\Users\<User>\AppData\Local\PortableApps\) rather than using the standard Program Files directory.
  • Filter/Exclusion: Exclude executables located in AppData\Local or AppData\Roaming if the parent folder name matches known portable app patterns (e.g., PortableApps, Portable, Apps) or if the file size is within a typical range for portable tools (