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3. Advanced Course

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  1. 1. What is Taproot?
  2. 2. Blockchain bridges – what are they?
  3. 3. What is Ethereum Plasma?
  4. 4. What is Ethereum Casper?
  5. 5. What is Zk-SNARK and Zk-STARK? 
  6. 6. What is Selfish Mining? 
  7. 7. What is spoofing in the cryptocurrency market? 
  8. 8. Schnorr signatures - what are they? 
  9. 9. MimbleWimble - what is it? 
  10. 10. What is digital property rights in NFT?
  11. 11. What are ETFs and what role do they play in the cryptocurrency market? 
  12. 12. How to verify a cryptocurrency project – cryptocurrency tokenomics 
  13. 13. What is the 51% attack on blockchain?
  14. 14. What is DAO, and how does it work?
  15. 15. Zero-knowledge proof – a protocol that respects privacy 
  16. 16. What is EOSREX?
  17. 17. What is Proof of Elapsed Time (PoET)?
  18. 18. Mirror Protocol – what it is? 
  19. 19. What are synthetic assets? 
  20. 20. How to create your own NFT? 
  21. 21. Definition of DeFi, and what are its liquidations?
  22. 22. New identity system - Polygon ID
  23. 23. Ethereum Foundation and the Scroll protocol - what is it?
  24. 24. What is Byzantine fault tolerance in blockchain technology?
  25. 25. Scalability of blockchain technology - what is it?
  26. 26. Interchain Security - new Cosmos (ATOM) protocol
  27. 27. Coin Mixing vs. Coin Join - definition, opportunities, and threats
  28. 28. What is Ethereum Virtual Machine (EVM) and how does it work?
  29. 29. Soulbound Tokens - what are they, and how do they work?
  30. 30. Definition of LIDO - what is it?
  31. 31. What are Threshold Signatures, and how do they work?
  32. 32. Blockchain technology and cyberattacks.
  33. 33. Bitcoin script - what it is, and what you should know about it.
  34. 34. What is zkEVM, and what are its basic features?
  35. 35. Do confidential transactions on blockchain exist? What is a Confidential Transaction?
  36. 36. Algorithmic stablecoins - everything you should know about them.
  37. 37. Polygon Zk Rollups ZKP - what should you know about it?
  38. 38. What is Web3 Infura?
  39. 39. Mantle - Ethereum L2 scalability - how does it work?
  40. 40. What is the NEAR Rainbow Bridge?
  41. 41. Liquid Staking Ethereum and LSD tokens. What do you need to know about it?
  42. 42. Top 10 blockchain oracles. How do they work? How do they differ?
  43. 43. What are Web3.js and Ether.js? What are the main differences between them?
  44. 44. What is StarkWare, and recursive validity proofs
  45. 45. Quant Network: scalability of the future
  46. 46. Polygon zkEVM - everything you need to know
  47. 47. What is Optimism (OP), and how do its roll-ups work?
  48. 48. What are RPC nodes, and how do they work?
  49. 49. SEI Network: everything you need to know about the Tier 1 solution for DeFi
  50. 50. Types of Proof-of-Stake Consensus Mechanisms: DPoS, LPoS and BPoS
  51. 51. Bedrock: the epileptic curve that ensures security!
  52. 52. What is Tendermint, and how does it work?
  53. 53. Pantos: how to solve the problem of token transfer between blockchains?
  54. 54. What is asymmetric encryption?
  55. 55. Base-58 Function in Cryptocurrencies
  56. 56. What Is the Nostr Protocol and How Does It Work?
  57. 57. What Is the XDAI Bridge and How Does It Work?
  58. 58. Solidity vs. Rust: What Are the Differences Between These Programming Languages?
  59. 59. What Is a Real-Time Operating System (RTOS)?
  60. 60. What Is the Ethereum Rinkeby Testnet and How Does It Work?
  61. 61. What Is Probabilistic Encryption?
  62. 62. What is a Pinata in Web 3? We explain!
  63. 63. What Is EIP-4337? Will Ethereum Account Abstraction Change Web3 Forever?
  64. 64. What are smart contract audits? Which companies are involved?
  65. 65. How does the AirGapped wallet work?
  66. 66. What is proto-danksharding (EIP-4844) on Ethereum?
  67. 67. What is decentralised storage and how does it work?
  68. 68. How to Recover Cryptocurrencies Sent to the Wrong Address or Network: A Practical Guide
  69. 69. MPC Wallet and Multilateral Computing: Innovative Technology for Privacy and Security
  70. 70. Threshold signature in cryptography: an advanced signing technique!
  71. 71. Vanity address in cryptocurrencies: what is it and what are its characteristics?
  72. 72. Reentrancy Attack on smart contracts: a threat to blockchain security!
  73. 73. Slither: a static analyser for smart contracts!
  74. 74. Sandwich Attack at DeFi: explanation and risks!
  75. 75. Blockchain RPC for Web3: A key technology in the world of decentralized finance!
  76. 76. Re-staking: the benefits of re-posting in staking!
  77. 77. Base: Evolving cryptocurrency transactions with a tier-2 solution from Coinbase
  78. 78. IPFS: A new era of decentralized data storage
  79. 79. Typical vulnerabilities and bridge security in blockchain technology
  80. 80. JumpNet - Ethereum's new sidechain
Lesson 79 of 80
In Progress

79. Typical vulnerabilities and bridge security in blockchain technology

Blockchain technology, which was created as the basis for cryptocurrencies, has evolved and is used in various sectors of the economy. One of the key elements that enable interoperability and collaboration between different blockchains are so-called bridges.

These bridges are critical elements in the blockchain ecosystem and their security is crucial for the integrity and reliability of the entire system. In this article, we will analyse typical security vulnerabilities of blockchain bridges and present strategies to effectively secure them.

What are blockchain bridges?

A blockchain bridge is a mechanism that connects two independent blockchains. Its purpose is to facilitate communication between them. For example, if you want to settle Bitcoin and use decentralised financial services (DeFi) on the Ethereum network, the corresponding blockchain bridge allows you to do so without having to sell your Bitcoin.

Bridges play a hugely important role in the entire blockchain ecosystem. They are essential for establishing interoperability between different blockchains. They work by utilising a variety of validation processes both on-chain and off-chain, which makes them vulnerable to various types of security breaches.

In practise, bridges store tokens that a user wants to transfer between different chains. Typically, bridges are implemented as smart contracts and accumulate a significant number of tokens as cross-chain transfers increase, making them an attractive target for potential hackers.

In addition, blockchain bridges offer further attack opportunities due to their complex structure involving multiple components. Therefore, fraudsters are highly motivated to target cross-chain applications  to loot significant sums of money.

Bridge security in the blockchain ecosystem is therefore of enormous importance.

Typical vulnerabilities in bridge security

  1. 51% Attacks are one of the biggest threats to blockchain security. In the case of bridges, such an attack can lead to the majority of the nodes operating the bridge being controlled, resulting in manipulation of the transmitted data. To counter this threat, consensus mechanisms that are resistant to such attacks must be used.
  2. Vulnerabilities in smart contracts. Bridges often use smart contracts to transfer information between different blockchains. However, flaws in the code of smart contracts can lead to security vulnerabilities that allow attackers to take control of the bridge. Regular security checks of the contract code are therefore essential.
  1. Exploitation of oracles. Blockchain bridges often use oracles or oracles for external information to obtain data outside the blockchain. Attacks on oracles can lead to manipulation of the transmitted data, which in turn affects the state of the contract on the other chain. Verification of oracle data and the use of decentralised data sources are key to ensuring security.
  2. Insufficient or too little on-chain verification. The process of on-chain verification, especially for bridges dedicated to specific dApps, is usually minimised. For these bridges, the execution of basic operations is performed by centralised backends. All other verifications are performed off-chain. This approach to bridges can lead to gaps that are very likely to be exploited by hackers.

Security vulnerabilities in blockchain bridges

First and foremost, the implementation of multilevel security that includes both the protocol layer and the application layer is crucial. The use of consensus algorithms such as PoW (Proof of Work) or PoS (Proof of Stake), and regular software updates help minimize the risk of 51% attacks.

Ensure the security of smart contracts. Regular security audits of intelligent contracts code are essential to detect and fix potential vulnerabilities. Using the latest programming standards, such as Solidity, and using secure design patterns are key to minimizing risk.

Decentralized data sources when using expectation. The use of decentralized data sources is recommended to protect against attacks on oracles. Using multiple oracles from different sources increases resistance to information manipulation and minimizes the risk of data errors.

Finally, education and awareness. Training the teams responsible for developing, maintaining and managing blockchain bridges is crucial. Awareness of the latest threats and security practices will allow teams to respond quickly to potential threats.


Securing blockchain bridges is a complex task that requires multiple security measures. A combination of layered security measures, code audits, the use of oracles and continuous education is key to maintaining integrity and security in the blockchain ecosystem.

Continuous improvement of security protocols and practises is critical given the dynamic nature of cyber threats.

Complete today’s lesson!

  1. What is Byzantine fault tolerance?
  2. Blockchain technology and cyber attacks.
  3. What are smart contract audits?