https://pnasis.gitlab.io/tags/reentracy/ Recent content in Reentracy on pnasis Hugo en-us Mon, 29 Jun 2026 14:16:35 +0300 https://pnasis.gitlab.io/posts/sekaictf-2026-blockchain-writeups-part-1-pp-farming/ Mon, 29 Jun 2026 14:16:35 +0300 https://pnasis.gitlab.io/posts/sekaictf-2026-blockchain-writeups-part-1-pp-farming/ <h2 id="introduction">Introduction</h2> <p>    After solving the cryptography challenge presented in the previous post, I decided to explore another category of <a href="https://ctftime.org/event/3113">SekaiCTF 2026</a>. This time, I focused on blockchain challenges, which offered a completely different set of problems centered around smart contract security and decentralized application logic. Unlike traditional binary exploitation or cryptographic attacks, blockchain challenges often require identifying flaws in contract design, state management and interactions between multiple contracts.</p> <p>    The challenge discussed in this post is <em><strong>PP Farming 1</strong></em>, an Ethereum smart contract challenge that demonstrates one of the most well-known vulnerabilities in smart contract development: <strong>reentrancy</strong>. Although this class of vulnerability has been extensively studied since the infamous <a href="https://cybernews.com/crypto/crypto-290m-kelp-dao-exploit-north-koreas-lazarus-group/">DAO exploit</a>, it continues to appear in Capture The Flag competitions because it teaches an important security principle that every smart contract developer should understand.</p>