Cybersecurity researcher Zakhar Fedotkin has demonstrated a significant vulnerability in PDF rendering that can impact the accuracy of pricing on digital invoices. His proof of concept reveals that discrepancies in how different browsers and operating systems render PDF files can lead to variations in displayed prices. For example, a PDF invoice might show £399 in Safari on macOS but display £999 in Google Chrome on Windows, potentially causing severe financial discrepancies.
The issue arises from the differing engines used by major browsers to render PDFs. Google Chrome employs PDFium, Safari uses its proprietary engine, and Firefox relies on PDF.js. Each engine handles interactive form fields and widget annotations differently, leading to inconsistencies in how the same PDF file is displayed. Fedotkin’s demonstration utilized the org.apache.pdfbox Java library to create a hybrid PDF exploiting these rendering differences.
The potential for financial mismanagement is significant. If an invoice shows one price on one platform and a different price on another, it can lead to confusion and incorrect payment amounts. For instance, a CEO might approve a payment of £399 based on what is displayed in Safari, only for the accounting department to process a payment of £999 when viewed in Google Chrome.
To mitigate this risk, businesses should ensure that all stakeholders use the same PDF viewer to maintain consistency in invoice processing. Additionally, developers and cybersecurity professionals should be aware of these vulnerabilities and implement safeguards to prevent potential exploitation. Fedotkin’s research highlights the need for caution and uniformity in digital invoice handling to avoid financial discrepancies.
