🧑‍⚖️Chain Re-org Vulnerability in Governance Voting Mechanisms

In blockchain governance systems, voting mechanisms are often designed with incremental proposal IDs to track and manage votes on different proposals. These IDs typically increment with each new proposal, creating an ordered system for users to cast their votes. However, this incremental system can introduce a significant vulnerability in the case of chain reorganizations (re-orgs). A re-org can enable attackers to front-run and back-run the voting process, manipulating the voting system to their advantage and potentially undermining the integrity of the governance process.

In this section, we will explore how chain re-orgs can affect governance voting mechanisms, particularly in systems where the proposal ID is incrementally assigned. We will walk through the potential exploits and offer mitigation strategies to prevent governance manipulation due to chain re-orgs.

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How Chain Re-orgs Affect Governance Voting

A chain re-org occurs when two competing versions of the blockchain exist temporarily, and one of the chains is discarded in favor of the other. This process causes transactions that were previously confirmed on the discarded chain to become invalid, and new transactions may take their place in the reorganized chain. In governance systems that rely on incrementally assigned proposal IDs, re-orgs can be exploited by malicious actors to front-run or back-run proposals, leading to skewed voting results.

Attack Flow: Front-running and Back-running Governance Proposals

1. Proposal Creation with Incremental IDs:

   • In many decentralized governance systems, each new proposal is assigned an ID based on the current total number of proposals. For example, Proposal 1 has an ID of 1, Proposal 2 has an ID of 2, and so on. This ensures a predictable sequence of proposals for voting.

2. Re-org Vulnerability in Proposal Voting:

   • During a chain re-org, if the proposal creation transaction is included in the discarded chain, an attacker can take advantage of the reorganization to manipulate the proposal creation process.

   • The attacker monitors the mempool for a pending proposal creation transaction. When a re-org occurs, the attacker submits their own proposal transaction during the re-org and takes the incremental proposal ID that was meant for the original proposal.

3. Front-running Proposal Creation:

   • The attacker submits a proposal before the legitimate proposal can be re-added to the reorganized chain. Because proposal IDs are incremental, the attacker can "steal" the proposal ID by submitting their proposal first, causing the legitimate proposal to be assigned a different, later ID.

   • This manipulation can affect governance outcomes by confusing voters, disrupting proposal ordering, or allowing the attacker to insert malicious or self-serving proposals.

4. Back-running the Voting Process:

   • After manipulating the proposal creation process, the attacker can back-run the voting process. For example, the attacker may manipulate the proposal ID sequence to trick users into voting for the wrong proposal or mislead participants by controlling the sequence and timing of proposal submissions.

   • Once the re-org resolves, the attacker has effectively front-run the proposal submission and back-run the voting process, gaining control over the governance process.