IMPORTANT: No additional bug fixes or documentation updates will be released for this version. For the latest information, see the current release documentation.

« Screensaver Plist File Modified by Unexpected Process SeDebugPrivilege Enabled by a Suspicious Process »

› › ›

Script Execution via Microsoft HTML Application

edit

Script Execution via Microsoft HTML Application

edit

Identifies the execution of scripts via HTML applications using Windows utilities rundll32.exe or mshta.exe. Adversaries may bypass process and/or signature-based defenses by proxying execution of malicious content with signed binaries.

Rule type: eql

Rule indices:

winlogbeat-*
logs-windows.*
logs-system.security*
logs-windows.sysmon_operational-*
logs-sentinel_one_cloud_funnel.*
logs-m365_defender.event-*

Severity: high

Risk score: 73

Runs every: 5m

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References: None

Tags:

Domain: Endpoint
OS: Windows
Use Case: Threat Detection
Tactic: Defense Evasion
Data Source: System
Data Source: Sysmon
Data Source: SentinelOne
Data Source: Microsoft Defender for Endpoint

Version: 1

Rule authors:

Elastic

Rule license: Elastic License v2

Rule query

edit

process where host.os.type == "windows" and event.type == "start" and
 process.name : ("rundll32.exe", "mshta.exe") and
  (
     (process.command_line :
        (
        "*script*eval(*",
         "*script*GetObject*",
         "*.regread(*",
         "*WScript.Shell*",
         "*.run(*",
         "*).Exec()*",
         "*mshta*http*",
         "*mshtml*RunHTMLApplication*",
         "*mshtml*,#135*",
         "*StrReverse*",
         "*.RegWrite*",
         /* Issue #379 */
         "*window.close(*",
         "* Chr(*"
         )
     and not process.parent.executable :
                  ("?:\\Program Files (x86)\\Citrix\\System32\\wfshell.exe",
                   "?:\\Program Files (x86)\\Microsoft Office\\Office*\\MSACCESS.EXE",
                   "?:\\Program Files\\Quokka.Works GTInstaller\\GTInstaller.exe")
     ) or

    (process.name : "mshta.exe" and
     not process.command_line : ("*.hta*", "*.htm*", "-Embedding") and process.args_count >=2) or

     /* Execution of HTA file downloaded from the internet */
     (process.name : "mshta.exe" and process.command_line : "*\\Users\\*\\Downloads\\*.hta*") or

     /* Execution of HTA file from archive */
     (process.name : "mshta.exe" and
      process.args : ("?:\\Users\\*\\Temp\\7z*", "?:\\Users\\*\\Temp\\Rar$*", "?:\\Users\\*\\Temp\\Temp?_*", "?:\\Users\\*\\Temp\\BNZ.*"))
   )

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Defense Evasion
- ID: TA0005
- Reference URL: https://attack.mitre.org/tactics/TA0005/
Technique:
- Name: System Binary Proxy Execution
- ID: T1218
- Reference URL: https://attack.mitre.org/techniques/T1218/
Sub-technique:
- Name: Mshta
- ID: T1218.005
- Reference URL: https://attack.mitre.org/techniques/T1218/005/
Sub-technique:
- Name: Rundll32
- ID: T1218.011
- Reference URL: https://attack.mitre.org/techniques/T1218/011/

« Screensaver Plist File Modified by Unexpected Process SeDebugPrivilege Enabled by a Suspicious Process »