Executive brief
RansomLook is a web application that tracks ransomware-related cryptocurrency transactions. The application fails to properly validate cryptocurrency addresses imported from external sources before displaying them in the browser, allowing an attacker to inject malicious JavaScript code that executes when users interact with wallet export features, potentially exposing sensitive information or performing unauthorized actions.
Technical details
This is a stored cross-site scripting (XSS) vulnerability in the cryptocurrency wallet detail view component. Cryptocurrency addresses and blockchain names sourced from external feeds (including the public crowd-sourced ransomwhe.re feed) are stored without sufficient validation and then embedded directly into inline JavaScript onclick handlers. Although Jinja HTML autoescaping is applied, it fails to protect against untrusted data inserted into JavaScript strings within HTML attributes because HTML entities are decoded before JavaScript interpretation. An attacker can craft a malicious cryptocurrency address containing quote characters and JavaScript syntax to escape the string literal and execute arbitrary code when a user clicks the wallet's CSV export button. Exploitation may not require authentication if the attacker can introduce a malicious wallet record into an upstream external data source. The patch validates cryptocurrency addresses and blockchain identifiers against a safe character set and replaces inline JavaScript handlers with data attributes and external event listeners.
Affected products
- RansomLook
Timeline
- 2026-08-24: disclosed