T1608.005Not expressible in Sigma

Link Target

Resource DevelopmentPRE

Where this stands

No Sigma rule can address this — the telemetry MITRE names has no Sigma logsource behind it.

This happens on infrastructure you do not own, so it never reaches your logs. MITRE's own guidance is internet scanning and threat intelligence, not log analysis.

What the technique is

Adversaries may put in place resources that are referenced by a link that can be used during targeting. An adversary may rely upon a user clicking a malicious link in order to divulge information (including credentials) or to gain execution, as in Malicious Link. Links can be used for spearphishing, such as sending an email accompanied by social engineering text to coax the user to actively click or copy and paste a URL into a browser. Prior to a phish for information (as in Spearphishing Link) or a phish to gain initial access to a system (as in Spearphishing Link), an adversary must set up the resources for a link target for the spearphishing link. Typically, the resources for a link target will be an HTML page that may include some client-side script such as JavaScript to decide what content to serve to the user. Adversaries may clone legitimate sites to serve as the link target, this can include cloning of login pages of legitimate web services or organization login pages in an effort to harvest credentials during Spearphishing Link. Adversaries may also Upload Malware and have the link target point to malware for download/execution by the user. Adversaries may purchase domains similar to legitimate domains (ex: homoglyphs, typosquatting, different top-level domain, etc.) during acquisition of infrastructure (Domains) to help facilitate Malicious Link. […]

Read it on attack.mitre.org

What MITRE says you would watch

AN2025
If infrastructure or patterns in malicious web content have been previously identified, internet scanning may uncover when an adversary has staged web content to make it accessible for targeting. Much of this activity will take place outside the visibility of the target organization, making detection of this behavior difficult. Detection efforts may be focused on other phases of the adversary lifecycle, such as during Spearphishing Link, Spearphishing Link, or Malicious Link.