remediatetheflag: open source platform to teach developers application security topics

Remediate the Flag

(Practical) Application Security Training Platform

Developers aren’t born knowing how to code securely and appsec training is often boring and does not provide practical examples. For the business, it is usually not possible to assess competency in secure coding and difficult to calculate ROI on security training.

RTF is an open source Practical Application Security Training platform that hosts application security focused exercises.

Candidates manually find, exploit, and manually remediate the code of a vulnerable application running in a disposable development environment accessed using a web browser. 100% hands-on training, no multiple choice questions involved.



  • Run vulnerable exercises in docker containers running in a sandboxed environment in the cloud
  • Provide users in seconds with a turn-key development environment already configured with selected exercise
  • Exercise focus on exploitation/remediation or secure coding and target the most common application security issues
  • User is provided with automated results checker to increase engagement
  • Deployable on AWS through CloudFormation, scales horizontally and vertically
  • Setup and Manage Organizations, Teams and Users
  • Get Stats at Organization, Region, Team and User level to quickly identify gaps
  • Setup Challenges targeting programming language or specific vulnerability classes
  • Reference the AppSecEU 2018 slides for a functional overview.

How Does it Work?

Candidates select an exercise, the RTF platform provisions a dedicated environment accessed through a web browser. Candidates then find and manually remediate vulnerable code in the RTF instance by referencing the instructions. Candidates can check in real time whether security issues were successfully remediated; they can take hints which affect their final score. When the exercise is completed, the platform provides automated results including code diff and logs. An assessor reviews the exercise results and, if necessary (wrong remediation approach), provides additional feedback to the candidate. It is possible to setup time-boxed tournaments specifying programming languages, developer groups (frontend vs backend, web vs non-web) and target vulnerabilities. Points are used to rank candidates on a “Leaderboard” so that they can compare themselves to their peers. Full stats are provided at candidate, team and organisation level indicating remediation ratio and time spent on each type of vulnerability and aggregated on category types. It is possible to add new exercises, and technologies and target any specific organization needs.