From Scores to Queues: Operationalizing Cross-Chain Obfuscation Signals for Smart-Contract Audits

Abstract: Obfuscation substantially increases the interpretation cost of smart-contract auditing, while the comparability and transferability of obfuscation signals across chains remain unclear. We present HObfNET as an efficient surrogate of Obfs_Tool (ObfProbe), enabling fast cross-chain scoring at scale. The model aligns well with tool outputs on Ethereum (PCC 0.9158, MAPE 8.20 percent) and achieves 8-9 ms per contract, a 2.3k-5.2k times speedup over second-level Obfs_Tool runs, enabling million-scale scoring. On large BSC, Polygon, and Avalanche corpora, we find systematic score drift: fixed-threshold transfer inflates and deflates candidate queues, motivating within-chain main and extreme thresholds (p99 and p99.9) and an actionable queueing strategy. The high-score tail exhibits rare selectors, external-call opcode enrichment, and low signature density; a proxy indicator is enriched in the BSC high-score queue, enabling secondary triage. Cross-chain reuse analysis shows tail enrichment and directional diffusion, with traceable same-hash cases across chains. In publicly alignable incident samples, all fall into the p99 queue; Transit Swap DEX Hack and New Free DAO Flash Loan exhibit cross-chain spillover, indicating real-world hit and prioritization value. We deliver a two-tier audit queue and cross-chain linkage workflow to support practical multi-chain security operations.