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Unusual Web Request

A machine learning job detected a rare and unusual URL that indicates unusual web browsing activity. This can be due to initial access, persistence, command-and-control, or exfiltration activity. For example, in a…

Description

A machine learning job detected a rare and unusual URL that indicates unusual web browsing activity. This can be due to initial access, persistence, command-and-control, or exfiltration activity. For example, in a strategic web compromise or watering hole attack, when a trusted website is compromised to target a particular sector or organization, targeted users may receive emails with uncommon URLs for trusted websites. These URLs can be used to download and run a payload. When malware is already running, it may send requests to uncommon URLs on trusted websites the malware uses for command-and-control communication. When rare URLs are observed being requested for a local web server by a remote source, these can be due to web scanning, enumeration or attack traffic, or they can be due to bots and web scrapers which are part of common Internet background traffic.

Detection logic

Its licence does not clear it for publishing here

Sunturai publishes a detection's own text where the licence it arrived under has been reviewed and permits it, and Elastic License 2.0 has not. The query as its source wrote it, its canonical form and the hash that pins this revision are in the workspace record.

Detection requirements

Platform
ESXiIdentity ProviderLinuxmacOSNetwork DevicesWindows

The rule states no platform. This is derived from the 3 ATT&CK techniques it maps to.

Known benign triggers

  • Web activity that occurs rarely in small quantities can trigger this alert. Possible examples are browsing technical support or vendor URLs that are used very sparsely. A user who visits a new and unique web destination may trigger this alert when the activity is sparse. Web applications that generate URLs unique to a transaction may trigger this when they are used sparsely. Web domains can be excluded in cases such as these.

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