This talks presents a security analysis of the Brazilian voting machine software based on our participation in the official tests organized by the national electoral authority. During the event, vulnerabilities in the software were detected and explored, with significant impact on ballot secrecy and integrity. We present scenarios where these vulnerabilities allow electoral fraud and suggestions to restore the security of the affected mechanisms. Additionally, flaws in the software development process are discussed in detail and we study how the free software methodology can potentially improve the security and transparency of the system.