What are Capture the Flag (CTFs) Competitions?

What are Capture the Flag (CTFs) Competitions?

Capture the flag aka CTF, there are two types of cut one is in the blockchain and another one is in cybersecurity. Cft is a cybersecurity event. 

Capture the Flag in cybersecurity

A capture the flag (CTF) contest is a unique kind of cybersecurity competition designed to challenge its participants to solve computer security problems and to capture and defend computer systems against any malicious attack.

The most common challenges in craft are Cryptography, Steganography, Binary exploitation, Web Exploitation, OSINT, Reversing or Reverse Engineering, Forensics, Pwn, Miscellaneous. Typically, these competitions are team-based and attract a diverse range of participants, including students, enthusiasts, and professionals.

In some challenges, the user has to find some specific hidden text of the serve,r, and hence this goal is called flag. The flag is typically a snippet of code, a piece of hardware on a network, or perhaps a file. The competition may progress through a series of questions, like a race. CTFs can be played in both ways individually or in teams.

The skills required for CTF based on the event, some demand highly professionals and some can be done by beginners too   Mainly, There are three formats of the cybersecurity CTF: attack-defense, Jeopardy-style, Mixed-style.

In attack defense, two teams play, one team is the attacker and another team is the defendant. It is usually played in two rounds, in the first round one team attacks on the other team’s system and defends their system and then they switch for the second round.

The attacking team can use numerous hacking tools to compromise the defending machines and the defending team can do anything with the rules to defend their machines against the attacking team. They aren’t allowed to leave the game in between, otherwise, they would be sanctioned and get eliminated. 

In jeopardy style, Jeopardy-style CTFs present competitors with a set of questions that reveal clues that guide them in solving complex tasks in a specific order. It is similar to the jeopardy games. More than two teams can play and here teams aren’t against each other. Several categories can be used. The game or task has to be completed within the deadline, specific times are given to complete a particular task. Once the timer stops, the game will get over. The team with the most points at the end wins. 

Mixed-style is a mixture of both attack-defense and Jeopardy-style. Here users or players can set attack-defense competition while having jeopardy challenges and vice-versa. 

These CTFs can be accessed globally or in some specific geographical boundaries. online CTF competitions are most likely to be Jeopardy-style. It’s easier to play solo and requires less coordination among players than an Attack and Defend competition. 

The very first cybersecurity CTF developed and hosted was in 1996 at DEFCON in Las Vegas, Nevada. DEFCON is the largest cybersecurity conference in the United States and it was officially started in 1993 by Jeff Moss.

Capture the Flag in Blockchains

“The Security Innovation Blockchain CTF has proven to be an incredible resource for developers and security experts to test their skills with practical exploitation challenges,” said Mick Ayzenberg.

At Security Innovation we are fascinated by the prospects of Blockchain technology Whether it be in finance, commerce, Internet services, or any of the other applicable sectors, we are excited by the potential for Blockchain to provide new efficiencies and disrupt existing models.

Security is the topmost priority, any data breaches may cause serious harm, and technology for security is most eminent. the consequences of an insecure Blockchain application will often result in immediate financial loss. This raises security concerns, as running untrusted code on systems that directly power a blockchain network is quite hazardous.

This is why the actions that smart contracts can do are very restricted. For example, Ethereum smart contracts can interact with the blockchain, store data in some kind of decentralized memory, receive input data, receive and send Ethereum assets, etc. Even with such restricted features, vulnerabilities exist and have been exploited several times in the past.

Applying Blockchain, we can solve a lot of problems that current technologies cannot do, which the most prominent is that there is no need to trust a third party anymore. Blockchain CTF is a decentralized application that includes vulnerable smart business contracts DApps with real-life use cases, ranging from decentralized trust funds and open-source lottery systems to ICOs and automated royalty agreements.

Blockchain CTF provides helpful hints and resources that assist users in learning more about the tools and methodologies used when developing, testing, and using DApps and smart contracts. Here players exploit Vulnerabilities to purloin fake testnet ETH and earn coins. According to the survey last year 2000 transactions were made.

There are several Blockchain CTF challenges which include Winners who are paid with DAI tokens on the blockchain, Two winners will be randomly drawn just for participating, First, five players to find all challenges win DAI tokens, with the view of privacy concern players aren’t required to fill personal details.

Security Innovation has conducted numerous security audits of blockchain and smart contract designs, used in stable coins, remittance services, and other solutions. 

Here are a curated list of blockchain security Wargames, Challenges, and Capture the Flag (CTF) competitions:



  1. Ethernet Lvl 0 Walkthrough
  2. Ethernet Lvl 1 Walkthrough
  3. Ethernet Lvl 2 Fallout Walkthrough
  4. Ethernet Lvl 3 Coin Flip Walkthrough
  5. Ethernet Lvl 4 Telephone Walkthrough
  6. Ethernet Lvl 5 Token Walkthrough
  7. Ethernet Lvl 6 Delegation Walkthrough
  8. Ethernet Lvl 7 Force Walkthrough
  9. Ethernet Lvl 8 Vault Walkthrough
  10. Ethernet Lvl 9 King Walkthrough
  11. Ethernet Lvl 10 Re-entrancy Walkthrough
  12. Ethernet Lvl 11 Elevator Walkthrough
  13. Ethernet Lvl 12 Privacy Walkthrough
  14. Ethernet Lvl 13 Gatekeeper 1 Walkthrough
  15. Ethernet Lvl 14 Gatekeeper 2 Walkthrough
  16. Ethernet Lvl 15 Naught Coin Walkthrough
  17. Ethernet Lvl 16 Preservation Walkthrough
  18. Ethernet Lvl 17 Locked Walkthrough
  19. Ethernet Lvl 18 Recovery Walkthrough
  20. Ethernet Lvl 19 Walkthrough


2.Capture the Ether


4.Security Innovation Blockchain CTF 

5.Cipher Shastra


1.Damn Vulnerable Defi

2.NCCGroup GOAT Casino

3.Damn Vulnerable Crypto Wallet

4.Crypto Hunt by p4d

5.Impossible by u/eththrowaway4


1.Paradigm CTF – 2021


2.0xPOLAND – 2020


3.AnChain CTF – 2020


4.Sharky CTF – 2020


5.RazzorSec CTF

HACON 2020




6.Donjon CTF – 2020


  1. Chain Heist – 2019


  1. “Capture the Coin” at Defcon 


  1. ConsenSys Diligence Ethereum Hacking Challenge – 2018


10.Code Blue PolySwarm Challenge – 2018


11.Real World CTF (Acoraida Monica Challenge) – 2018


12.Author Solidity CTF


Part 1 – Function Types

Part 2 – Safe Execution

Part 3 – HoneyPot

Part 4 – Read the Fine Print

Part 5 – Mirror Madness Solid


13.ZeroNights ICO Hacking Contest – 2017


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