Yeah. The dual file format trick reminded me of the GIFAR exploit where you take advantage of the fact that GIFs are header-based and JARs are footer-based. In

Yeah. The dual file format trick reminded me of the GIFAR exploit where you take advantage of the fact that GIFs are header-based and JARs are footer-based. In the present case, one format (PNG) is header-based and the other format (HTML) is headerless and generally tolerant of weird data.