First Partner Bank

Researcher Achieves SSTI-Based Defacement of First Partner Bank Web Service on Standoff 365

A security researcher known as grizzzer detailed a full attack chain that resulted in defacing the authorization page of the First Partner Bank digital banking service inside the Standoff 365 online polygon. The demonstration began with a successful DNS zone transfer against the fpb.stf domain, revealing the dbo.fpb.stf host that hosted the target application. After identifying the Node.js, Express, and React stack, the researcher discovered that the receipt generation endpoint accepted an undocumented pretty parameter that was passed directly into the Pug template engine. This led to a server-side template injection vulnerability that was escalated to a Node.js reverse shell. With code execution, the attacker located and modified the translation.json localization file, replacing the welcome message with the string pwned by VON visible to all users. The write-up concludes with concrete hardening recommendations including disabling zone transfers, avoiding direct spread of req.query into templates, and restricting outbound connections.