WeepSteel Strikes: How a Legacy Sitecore Flaw Became Hackers’ Playground
Threat actors are exploiting a zero-day vulnerability in legacy Sitecore deployments using CVE-2025-53690 to deploy WeepSteel malware. This misconfiguration flaw allows attackers to execute malicious payloads, leading to remote code execution. Sitecore advises replacing static machine keys and ensuring encryption to mitigate this vulnerability.
Hot Take:
Looks like some Sitecore deployments have been left wide open for a zero-day party, and the uninvited guests are having a blast with WeepSteel! If your Sitecore is still living in the pre-2017 era, it might be time to say goodbye to that nostalgic old ASP.NET machine key before it invites some unwanted drama.
Key Points:
- A zero-day vulnerability in legacy Sitecore deployments is being exploited to deploy WeepSteel malware.
- The vulnerability is due to a ViewState deserialization flaw involving a reused ASP.NET sample machine key.
- Attackers gain remote code execution by targeting a specific endpoint and deploy reconnaissance tools like WeepSteel.
- Subsequent attack stages include privilege escalation, data exfiltration, and persistence mechanisms.
- Sitecore has issued guidance to replace static machine keys in affected deployments to mitigate the vulnerability.
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