Resolv Academy: Tracing through the opaque bridges
Written by: Pawel Tutka
**Navigating through the DeFi Challenge of a high-risk Bridges **
This article marks the beginning of Resolv Academy, a new series of educational blogs where we explain how our protocol would handle risk associated with operating in the Web3 ecosystem. In this first edition, we focus on one of the most critical challenges: ensuring that Resolv itself will remain secure when dealing with funds coming directly from high-risk bridge protocols. In particular, we will outline how the protocol would respond to the risks tied to wrapping assets that originate from bridges without transparency, such as those lacking a public explorer.
**Understanding Bridge Operations **
A Simplified Flow Tracking funds through bridge protocols presents unique challenges that can obscure the source of assets. Here's an explanation of how bridge transfers typically work:
** Step 1: Asset Lock**
User locks original assets in a smart contract on the source blockchain (e.g., Ethereum)
** Step 2: Token Minting**
** **Equivalent wrapped tokens are minted on the destination blockchain (e.g., TRON)
** Step 3: Source Obscuring **
Original source of funds becomes difficult to trace as tokens move through the bridge protocol
**Profile of a high-risk Bridge protocol **
While using well-established bridges that are transparent and provide their own explorers makes fund tracing far more straightforward, the situation changes dramatically when this visibility is missing. The very fact that a significant amount of funds originate from a bridge protocol known for lacking a public explorer is, in itself, a strong red flag. This lack of transparency not only complicates monitoring but also raises immediate concerns about the reliability of the source.
This process creates significant challenges for tracking asset origins. Once assets cross a bridge, traditional blockchain explorers often lose the ability to trace back to the original source, creating potential blind spots in monitoring and risk assessment. Several key factors can significantly elevate the risk profile of a bridge protocol:
All of the above makes certain bridges effectively function as mixing services.
Our approach to mitigate the risk
At Resolv, we are building a protocol that would be in the future protected by a risk management system designed to address and mitigate posed risks, including these of a bridge-related challenges:
Advanced Detection
System will automatically flag transactions when funds arrive directly from high-risk addresses including bridges, creating immediate visibility into potential exposure.
Proactive Suspension
When addresses associated with high-risk bridges initiate a transfer, our protocol will temporarily suspend asset wrapping until our security team can conduct a thorough risk assessment.
Protocol Protection
This approach prevents the protocol from processing potentially tainted assets before they enter the system, keeping alignment with compliance standards.
Tracing through the non-transparent high-risk bridges
When a transaction monitoring system flags an address for further investigation, the next step is to examine the origin of the funds. This would be relatively straightforward if the assets passed through a transparent bridge with its own public explorer. In the case of opaque bridges, those without public explorers, the process is unfortunately more complex.
Here is how we plan to apply a backwards-tracing approach, and how such a method could be used to trace through non-transparent bridge protocols (backwards or forwards):
1. Identify the blockchain transaction where funds enter or leave a bridge
During that step, for training purposes, we will use a publicly available blockchain explorer which allows us to filter through the exact date and the amount - Arkham - intel.arkm.com.
On 08/29/2025 at 21:11:59, transaction 0xec...0924 shows that approximately 130,700 USDT entered our wallet of interest (0xa0...d6dc) from a bridge protocol operating at address 0xa0b...e26. Arkham attributes this address to the Defiway bridge.
A transaction of this size, executed through a bridge that we would classify as high-risk due to the lack of its own public explorer, should be flagged as suspicious and marked for further review.
2. Trace the asset flow backward or forward across all chains, until finding out where the tokens were originally locked or sent.
In order to map the counterpart transaction on the original/destination chain, even if the bridge itself does not provide public visibility we need to correlate patterns such as timing, amounts, and associated addresses to reconstruct the missing link.
Using Arkham, we would be able to review incoming and outgoing transactions from the bridge across multiple chains and attempt to match them with previously identified transaction details.
However, as illustrated below, during a span of nearly 60 minutes no candidate transactions appeared for the originating address. This demonstrates that while Arkham covers a wide range of blockchains, it may not yet include the one from which the bridge originated.
Does this mean that due to the lack of Defiway's own explorer, funds would become untraceable? Not necessarily. Several insights could still guide the investigation:
-
The name of the bridge
-
The blockchains covered by Arkham
-
Bridge output identifiers
With this information, we could narrow down potential blockchain candidates and move toward identifying the smart contract address used by Defiway.
Our logical starting point would be TRON given its speed, volume, and the fact that, in this case, it is not covered by Arkham. To proceed, we would use Defiway to conduct a test bridge transaction of USDT on TRON, allowing us to analyze the transaction data directly.
Through this, we could attribute and label the relevant Defiway contract address on TRON: TLEMNt...21H.
We would then turn to an open-source TRON explorer, such as OKLink, to match the previously identified transaction details.
As we can see above, on 08/29/2025 at 21:06:18 - roughly five minutes before the bridged funds appeared in our wallet of interest - transaction 94fb...8b459 was executed on the TRON blockchain, transferring approximately 131,000 USDT. The alignment of both timing and amount is a key indicator in backwards tracing through opaque bridges, as it allows us to reliably correlate transactions across chains. This correlation points to the originating address from which these tokens were bridged: TNN...sJjH.
Thanks to this form of backwards tracing, we would be able to assess risk more accurately and examine the full exposure of the address that initiated the bridge. The final decision on whether the receiving address should be permitted to proceed with wrapping would depend on the outcome of that assessment.
Such an approach could be applied to all tracing efforts involving opaque bridges that lack their own explorers, making it possible to reconstruct/follow the swaps and asset movements.
Conclusions
Tracing funds through bridges, especially opaque ones without public explorers, remains one of the most significant challenges in the Web3 ecosystem. By applying a backwards/forward-tracing methodology, it is possible to reconstruct the origin/destination of assets even when transparency is limited.
By combining open-source explorers like Arkham Intelligence with test-transfer techniques, we could attribute and label addresses to entities that were previously unavailable.
This approach would allow Resolv to flag suspicious flows, evaluate the exposure of specific addresses, and decide whether subsequent actions such as wrapping should be permitted. In doing so, the protocol could strengthen its resilience against hidden risks that might otherwise compromise system integrity.
Lessons & Takeaways
Not all bridge protocols are equal. The absence of public explorers and built-in security features makes some of them effectively function as mixing services.
Correlation matters, as matching timestamps and amounts across chains is a key method for tracing through opaque bridges.
Risk management is important for the ecosystem - by flagging and reviewing high-risk flows, Resolv would ensure that potential threats are addressed before they affect the system.
Risk cannot be eliminated, but it can be controlled by proactive monitoring that should allow the protocol to stay ahead of threats in a complex Web3 environment.