The current Axe Parser package includes a copy of RabbitSign, but it does not include the license, copyright statements, corresponding source code, or in fact, any acknowledgement of the program's origin. Instead, it contains what is apparently a README file for Wabbitsign (which is an unrelated program with a similar name and function.)
RabbitSign is free software, licensed under the
GNU General Public License. That means that anyone is allowed to use, copy, or modify it however they like. It also means that if you distribute it, you have a responsibility to inform users about their rights (including telling them where they can get the source code.) It's up to you how you do so, provided you comply with sections 4-6 of the GPL. What I would suggest, however, is that you simply include the COPYING and README files from the RabbitSign binary package (note that the README file includes a URL where the source code can be found.)
Please fix this as soon as possible. Users have a right to know where the software they're using came from, and what they are allowed to do with it.