Network Connection via Compiled HTML File

Last updated 2 months ago on 2025-03-20

Created 5 years ago on 2020-02-18

About

Compiled HTML files (.chm) are commonly distributed as part of the Microsoft HTML Help system. Adversaries may conceal malicious code in a CHM file and deliver it to a victim for execution. CHM content is loaded by the HTML Help executable program (hh.exe).

Tags

Domain: EndpointOS: WindowsUse Case: Threat DetectionTactic: ExecutionData Source: Elastic DefendData Source: SysmonLanguage: eql

Severity

low

Risk Score

MITRE ATT&CK™

Execution (TA0002)(opens in a new tab or window)

↳ User Execution (T1204)(opens in a new tab or window)

Defense Evasion (TA0005)(opens in a new tab or window)

↳ System Binary Proxy Execution (T1218)(opens in a new tab or window)

License

Elastic License v2(opens in a new tab or window)

Definition

Rule Type

Event Correlation Rule

Integration Pack

Prebuilt Security Detection Rules

Index Patterns

winlogbeat-*logs-endpoint.events.process-*logs-endpoint.events.network-*logs-windows.sysmon_operational-*

Related Integrations

endpoint(opens in a new tab or window)

windows(opens in a new tab or window)

Query

sequence by process.entity_id
  [process where host.os.type == "windows" and process.name : "hh.exe" and event.type == "start"]
  [network where host.os.type == "windows" and process.name : "hh.exe" and
     not cidrmatch(destination.ip, "10.0.0.0/8", "127.0.0.0/8", "169.254.0.0/16", "172.16.0.0/12", "192.0.0.0/24",
       "192.0.0.0/29", "192.0.0.8/32", "192.0.0.9/32", "192.0.0.10/32", "192.0.0.170/32", "192.0.0.171/32",
       "192.0.2.0/24", "192.31.196.0/24", "192.52.193.0/24", "192.168.0.0/16", "192.88.99.0/24", "224.0.0.0/4",
       "100.64.0.0/10", "192.175.48.0/24","198.18.0.0/15", "198.51.100.0/24", "203.0.113.0/24", "240.0.0.0/4", "::1",
       "FE80::/10", "FF00::/8") and
     not dns.question.name : "localhost"]

Install detection rules in Elastic Security

Detect Network Connection via Compiled HTML File in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(opens in a new tab or window).