Abstract: Visible light communication (VLC) systems commonly employ cyclic redundancy check (CRC) to ensure frame integrity, yet targeted integrity attacks against CRC-protected VLC links remain largely unexplored. To the best of our knowledge, this paper presents the first intelligent reflecting surface (IRS)-assisted CRC-collision covert injection framework for VLC systems. Under the on-off keying (OOK)/intensity modulation and direct detection (IM/DD) model, a symbol-level attack model is developed for a system consisting of a main receiver and a cooperative receiver. Subject to the non-negative optical intensity constraint, the attack action is decomposed into two physically realizable operations, namely injection enhancement for 0→1 flipping and interception-based attenuation with controlled backfill for 1→0 flipping, where the controlled backfill is implemented through a weak-backfill constraint. On this basis, CRC-collision construction, dual-mode IRS switching, and joint waveform-IRS optimization are integrated to realize targeted symbol manipulation while suppressing anomalies in cooperative detection statistics. Simulation results show that the proposed method achieves a frame-level attack success rate of 98%, with a CRC pass rate of 98% and an overall detection rate of 8%. Ablation studies further verify that dual-mode switching, ratio-deviation control, and the weak-backfill mechanism are all essential to maintaining both attack effectiveness and covertness. The proposed framework provides a tractable model for studying integrity-oriented stealth attacks in VLC systems and offers useful support for the design of corresponding detection and protection mechanisms.

Key words: visible light communication, intelligent reflecting surface, covert injection attack, cyclic redundancy check, cooperative detection