HotelAlfa

Hunt Hypothesis

This detection targets adversary behavior associated with the HotelAlfa malware family, specifically identifying its unique code signatures within endpoint processes to uncover potential initial footholds or lateral movement activities. Proactively hunting for this indicator in Azure Sentinel is critical because early identification of these low-severity artifacts allows the SOC team to correlate them with broader threat intelligence before they escalate into significant data exfiltration incidents.

YARA Rule

rule HotelAlfa
{
	meta:
		copyright = "2015 Novetta Solutions"
		author = "Novetta Threat Research & Interdiction Group - trig@novetta.com"
		Source = "58dab205ecb1e0972027eb92f68cec6d208e5ab5.ex_"

	strings:
	
	$resourceHTML = "RSRC_HTML"
	/*
		8A 0C 18  mov     cl, [eax+ebx]
		80 F1 63  xor     cl, 63h
		88 0C 18  mov     [eax+ebx], cl
		8B 4D 00  mov     ecx, [ebp+0]
		40        inc     eax
		3B C1     cmp     eax, ecx
		72 EF     jb      short loc_4010B4
	*/

	$rscsDecoderLoop = {8A [2] 80 F1 ?? 88 [2] 8B [2] 40 3B ?? 72 EF}

	condition:
		$resourceHTML and $rscsDecoderLoop in ((pe.sections[pe.section_index(".text")].raw_data_offset)..(pe.sections[pe.section_index(".text")].raw_data_offset + pe.sections[pe.section_index(".text")].raw_data_size))
}

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 2 string patterns in its detection logic.

• Source Rule

False Positive Guidance

Here are 5 specific false positive scenarios for the HotelAlfa detection rule in an enterprise environment, including suggested filters and exclusions:

• Scenario: Microsoft Defender Antivirus Scheduled Scans

  • Context: The daily or weekly scheduled scan initiated by MsMpEng.exe (Microsoft Defender) often scans large archives containing known benign files that match the HotelAlfa signature. This is common during off-hours maintenance windows.
  • Suggested Filter/Exclusion: Create an exclusion for the process path \Program Files\Windows Defender\MsMpEng.exe and filter out alerts where the file hash matches a known “Clean” baseline in your SIEM (e.g., exclude events with threat_category = 'Scheduled Scan').

• Scenario: SCCM/MECM Software Deployment Packages

  • Context: During mass software deployment via Microsoft Endpoint Configuration Manager (SCCM), the ccmexec.exe service extracts and stages application packages. These packages frequently contain installer executables or scripts that trigger the HotelAlfa YARA rule before being fully deployed to endpoints.
  • Suggested Filter/Exclusion: Exclude alerts originating from the parent process ccmexec.exe located in \Program Files\Microsoft Configuration Manager\. Additionally, filter by file extension .msi and .cab within the specific deployment folder path (e.g., \Software Distribution\).

• Scenario: Enterprise Backup Agent Operations

  • Context: Agents like Veeam Backup & Replication or Commvault perform incremental backups of critical data directories. The backup engine (VeeamAgent.exe or cvpfsd) reads and temporarily stages large datasets, often triggering the rule on benign configuration files or logs that resemble the HotelAlfa pattern.
  • Suggested Filter/Exclusion: Implement a process-based exclusion for known backup agents (