Report was a nice little challenge, we were presented with a PDF file in which Mr. Belford had written up for the FBI of the Gibson hack by Joey. The challenge alluded to Mr. Belford hiding something within the file. An initial look at the Report.pdf file nothing really stood out, except some troll flags 😀
So we took this challenge to the command line. Our first pass at the file, running strings and other useful commands nothing really stood out to us. Giving our tired eyes a break, we came back to Report.pdf later in the CTF timeframe. Again running strings we started to notice a pattern specifically within object 146:
We noticed that the last two digits of the second column of object 146 had similar hex digits/ascii printable characters. One thing to note is the string was in reverse so we had to start from the bottom and make our way to the top.
We tried or hand at cutting this column out and running some command line kung fu that totally failed… a little bit but when the output was returned we were hopeful and caught a glimpse at the flag 😀
So we decided to just take the string of hex and use xxd to convert the hex to ascii.