Cross-chain köprüler: yapısı, türleri ve zafiyetleri

The crypto market has long become multichain. Assets circulate across dozens of independent networks, including Ethereum, TRON, Solana, and BNB Chain. When users needed the ability to move tokens freely between these ecosystems without intermediaries and centralized exchanges, the blockchain bridge appeared. It became the foundation of cross-chain infrastructure and opened new possibilities, but at the same time added risks.

In this article you will learn:

• how a bridge actually “wraps” tokens instead of sending them directly;
• why bridges remain the most vulnerable link in DeFi;
• how to check a bridge crypto for security before using it.

Although technologies are constantly evolving, the security of crypto bridges still remains a serious challenge. Bugs in code and validator key leaks often lead to multimillion-dollar losses. Therefore, for every user performing a cross-chain transfer of assets, it is important to understand the principles of such systems and be aware of the potential risks.

Every bridge essentially holds the original assets in escrow and issues their digital copy, so its reliability directly determines the security of the entire cross-chain infrastructure.

A blockchain bridge, or bridge, is a tool that makes it possible to move tokens between different networks, for example from Ethereum to BNB Chain or TRON. Such a bridge does not send the asset directly; it uses the Lock & Mint principle, which means “lock and issue.”

It is worth remembering that a wrapped token depends on the lock contract or a custodian. If the custodian encounters an error, freezes assets, or loses access, the wrapper may lose its backing and depreciate, even if the bridge itself was not hacked.

Imagine you want to send 100 USDT from the Ethereum network to the BNB Chain network using an eth bridge. The bridge’s smart contract on Ethereum locks these tokens, and the linked contract on the bnb chain bridge issues the same amount of wrapped BEP-20 assets to your address. These new coins are called wrapped tokens; they act like digital IOUs backed by the original funds locked in the first network.

The original USDT remain in place until the owner decides to bring them back. In that case, the wrapped tokens are burned, and the originals are unlocked and returned to the user.

To understand the mechanics, it is worth looking at the basic architecture. A bridge is a system of two smart contracts that operate in different networks, and an intermediary—usually an oracle or a group of validators—monitoring both blockchains.

The workflow looks like this:

• the user sends 100 USDT to the smart contract on the first network;
• the contract accepts the tokens and temporarily locks them;
• the intermediary, for example an oracle, records the operation and relays the information to the second network;
• in the second network, a smart contract issues the same amount of wrapped tokens and credits them to the user;
• when the user decides to return the assets back, these tokens are burned, and the original coins become available again in the first network.

In addition to code vulnerabilities, network factors also affect security. A block rollback (reorg) is possible, in which the lock operation is canceled but minting has already been carried out. Sometimes there is no chainId check, which creates a risk of transaction replay (replay attacks). In addition, bridges are vulnerable to MEV attacks, where a confirming transaction is intercepted before inclusion in a block, giving the attacker a temporary advantage.

This operating principle helps synchronize the state of assets across different networks and does not force the user to fully trust one party. However, vulnerabilities lurk in this very mechanism, since a failure in any element can lead to loss of funds.

There are different types of bridges that differ in degree of decentralization, trust model, and method of asset custody. How exactly the system is built affects not only speed but also the safety of funds.

• Centralized bridges (Custodial) are managed by a single company or exchange. In this case, the user hands over their tokens to the bridge operator, who locks them and issues an equivalent in another network. This option can be compared to an internal exchange on a CEX, where everything happens quickly and simply. The main advantage of such solutions is high speed, a clear interface, and no need to delve into technical details. But centralized bridges also have a weak side, since the user fully trusts the operator with the custody of funds. If the company suffers a hack or decides to suspend operations, access to assets may be lost.
• A decentralized bridge (Non-custodial) operates without a single control center. Here the swap takes place using smart contracts and a network of validators that confirm every event in both networks. Examples of such solutions are the wormhole bridge and multichain, which for a long time were among the most popular. Their main advantage is transparency and no need to trust a specific organization. All operations are recorded on the blockchain, and transaction verification is distributed among many nodes. However, full automation makes such systems vulnerable to bugs in the code, which can lead to exploits and loss of funds.

In addition, bridges can be divided by direction of operation. One-way solutions allow moving tokens only from one network to another, without reverse exchange. Two-way bridges provide movement of assets in both directions, which makes them more flexible and convenient for users. These systems have become the standard in DeFi because they simplify the return of funds and support stable liquidity between networks.

Mini-table

When choosing a bridge, it is important to look not only at the type, but also at the level of openness and audit. Reliable projects publish code audit reports, run active bug bounty programs, and limit the amount that can be issued in a single cycle.

Modern projects increasingly use hybrid models that combine elements of both approaches. In them, some functions are performed by smart contracts, and some are controlled by centralized validators. This makes it possible to find a balance between speed and security, reducing risks while maintaining user convenience.

According to Chainalysis and DefiLlama, over the past years more than half of all losses in the DeFi sector have been related to attacks on bridges. For hackers, such projects are especially attractive because their smart contracts hold large sums of locked tokens.

The main causes of vulnerabilities are associated not only with code, but also with human factors. Analysis of major incidents shows that problems most often arise from three types of errors:

• bugs in smart contracts, due to which attackers can trick the system and issue unbacked tokens. This is exactly how the wormhole bridge hack happened in 2022, where more than $325 million was stolen;
• compromise of validator keys, when hackers gain control over the governance system and can withdraw assets, as happened in the hack of the Ronin bridge from Axie Infinity, where losses exceeded $600 million;
• manipulation of oracles, which are responsible for transmitting data between networks; if they are spoofed, a bridge can issue tokens without an actual deposit.

Each of these scenarios shows that security depends not only on technology, but also on the level of control and transparency embedded in a bridge’s architecture. Crypto bridges are as complex to operate as they are to break. When a system has many components and logical links, the likelihood of error or breach becomes significantly higher.

The main rule is that any cross-chain operation always carries increased risk. Before using a bridge, you should conduct your own check and make sure the sources are authentic.

You can read more about how to spot scams and protect your assets in the article on crypto fraud.

To reduce risks when using bridges, it is enough to follow a few simple rules:

• always verify links, as scammers often copy popular defi bridge and disguise themselves as well-known projects; take addresses only from official websites or verified Discord and X channels;
• pay close attention to permissions; do not grant a bridge full access to your tokens, especially for an unlimited period; a detailed explanation can be found in [link to the article “Signing transactions: how to understand what you are actually approving on the blockchain”];
• start with a small amount, for example ten or twenty dollars, and make sure the transfer actually goes through and the asset can be returned;
• avoid unknown projects that promise instant transfers or zero fees—such offers often turn out to be a scammer’s trap.

Following these simple rules helps maintain control over funds and reduce the likelihood of losing tokens.

The TRON ecosystem actively interacts with other networks through route aggregators. Services like tron justmoney router and tron openocean are not standalone bridges; they act as routers that use third-party bridges under the hood. They select the optimal exchange path, and at the output the user receives a wrapped token or a liquidity swap, depending on available liquidity.

A distinctive feature of USDT is that it exists simultaneously in several networks, including TRC-20, ERC-20, and BEP-20.

Because of this, transferring usdt between networks has become one of the most common operations in crypto. However, there is no official usdt trc-20 bridge. Scammers often take advantage of this by creating fake sites and bridges that promise fast and free swaps.

To safely move bridge usdt from TRC-20 to ERC-20, it is best to use a major centralized exchange or a vetted decentralized bridge with proven liquidity. If the goal is only to reduce fees for transfers within TRON, then no bridge is needed—within the network you can save on fees using the Tron Pool Energy service.

Blockchain bridges connect different ecosystems and form the backbone of DeFi infrastructure. Without them, the existence of cross-chain platforms and the free movement of liquidity between networks would be impossible. But convenience always comes with risk, since complex contracts, code bugs, and human factors often lead to multimillion-dollar losses.

You should use bridges only when it is truly necessary. For routine transfers, it is more reliable and cost-effective to choose a centralized exchange. If you work with decentralized solutions, pay attention to those that have been audited and used by the community for a long time.