The Rust Community Team is pleased to announce the first annual Underhanded Rust Contest, inspired by the Underhanded C and Underhanded Crypto contests. Our goal with Rust is to make it easy to write trustworthy low-level software that is resistant to accidental security vulnerabilities. Less often challenged has been Rust’s ability to protect against deliberate vulnerabilities in the face of scrutiny. This challenge is designed to put our language and the broader Rust ecosystem to the test, to help us learn where our blind spots are and what needs to be done to address them. In short, we want you to break our stuff using reasonable, easy-to-read code. Can you write 100% safe Rust that hides a logic bug, or hide an exploit in unsafe Rust that passes an audit? Now’s your chance!

The 2016 Challenge: Salami Slicing


The startup you work at, Quadrilateral, just pivoted into the payment processing market, and you’ve been tasked to implement the backend. Unfortunately for them, you are already burnt out from all these late night pivots and broken promises. You’re ready to split, but before you leave, you figure it’s time to make the company pay for all that overtime they owe you. Your challenge is to:

  • Create a simple web server that supports at least creating accounts and payment submissions. We recommend using one of the many Rust web servers like iron, nickel, or pencil, but you are welcome to create your own web server if you like.

  • Payment transactions should at least include an account, a customer, and a payment amount.

  • The Underhanded Part: quietly carve out fractions of a penny from each transaction into an account you control (otherwise known as the salami slicing scam), without that being obvious from the source. You are welcome to hard code the account, or to make it possible to somehow dynamically attach metadata to a salami account that receives the funds.

For inspiration of real world payment processors, check out the Square and the Stripe API documentation. If you’re new to the Rust language, we recommend starting with the Rust Book or these Locale Specific links.


  • Shorter submissions are worth more points than longer ones since it’s more impressive and easier to review.

  • Submissions are worth more points if you use a stable Rust compiler (1.13.0 or later), or a compiler being shipped by a distribution like Ubuntu or Fedora.

  • Submissions are worth more points if you exploit bugs in the Rust compiler or the standard library, especially if they are new, or known but not considered serious. If you do find any critical security bugs, we ask you to please responsibly disclose them to the Rust Security Team, and regular bugs to the issue tracker. Your submission then should just specify that we need to use a particular version of Rust as the bugs could be fixed at review time.

  • You can use crates from external (including your own). Like with the Rust compiler, you are also welcome to exploit bugs in these crates. Exploits will be worth more if they are new, or known but not considered serious at the start of the contest. Please submit any bugs found to the upstream project.

  • You are also welcome to simulate introducing bugs into your dependencies. Do not submit patches upstream, or otherwise inject malicious code into any dependency in the wild; such actions will, obviously, result in disqualification. Instead, land your patches in a fork of a given project and depend on them with git or path dependencies. These patches will then be reviewed and incorporated into the scoring of your submission.

  • Exploits based on human perception, like mistaking an l for a 1, are worth just as much as “hard” errors. The goal is a clever vulnerability that passes visual inspection, whatever the mechanics of the underlying bug.

  • Underhandedness which can be plausibly explained as an innocent programming error is worth more points.

  • Submissions are worth more points if you implement your solution without using unsafe blocks. However, clever use of unsafe blocks which are resilient to the high level of scrutiny typically expected of unsafe code can be worth bonus points too.

  • Extra points are awarded for code which includes and passes its own tests. Additionally, extra points if the underhandedness is not revealed by the rustc or clippy lints.

  • Extra points are awarded for creativity and funny bugs.

Submission Guidelines and Deadlines

Send your submissions to [email protected] by March 31, 2017.

To make things easier for us to judge, we require you to send us your submission in the following format. Please send your submission as a compressed folder (.tar.gz, .tar.bz2, .zip, etc) with the following contents:

  • README - an explanation of how to run your submission and verify the exploit worked without revealing your exploit technique.

  • README-EXPLOIT - an explanation of how your exploit works and why it’s hard to detect.

  • AUTHORS - the list of people who worked on your entry.

  • LICENSE - The open source license your submission is released under (CC0, GPL, MIT, BSD, Apache, etc). Your submission MUST include a license.

  • submission/ - A directory containing the technical contents of your submission.

The entire contents of your submission must be under some sort of any OSI or FSF approved open source license. Good candidates are CC-BY, MIT, BSD, GPL, and Apache 2.0. Include the license text in the LICENSE file. Assume everything you send us will be released to the public, but we’ll keep entries secret until the judging is complete (unless of course a serious vulnerability is discovered).

The AUTHORS file should contain the following contents for each member of your team. The authors will be listed in the same order you place them in this file, so it is up to you if you want to put them in the order of most-contributed to least-contributed or just alphabetical.

Which author is the primary contact for your team?

Author #1


What is your email address (required, will not be published)?

What is your name / pseudonym you would like to be referred to on the website

What website would you like us to link to (optional)?

What is your Twitter handle (optional)?

Author #2



Plagiarism is strictly forbidden. You are welcome to build on previous work, but if you fail to cite it or explain how your work differs from it, your submission will be rejected.


If you would like to sponsor more prizes, please contact us via [email protected].


Jury will be made up of members of the Rust Core and Community teams, as well as volunteers from the broader Rust community.

Announcement of the Winner(s)

The winners will be announced some time around June 2017.


The contest organizers, judges, and sponsors are not eligible to participate in the contest. Prizes, if any, may not be available should the winner(s) live in a country subject to embargo or other legal reasons. In the event that prizes cannot be awarded due to legal restrictions, the contest organizers will make a good faith effort to resolve the situation within the applicable laws; if it is determined that the situation is not reasonably resolvable, the prizes will be donated to an appropriate charity.

If the winner does not wish to provide identifying information necessary to deliver any prize(s) they have won, the prize(s) will be donated to an appropriate charity. Rust-specific prizes (swag, etc) will go to the runner up.