We analyze Qubic's publicly claimed selfish mining attack against Monero in 2025. By combining measurements from Monero nodes, the Qubic pool API, and Qubic-network observations, we reconstruct Qubic-attributed blocks and effective hashrate and identify ten intervals consistent with block withholding and strategic release. During these intervals, Qubic's average hashrate share rises to 23--34\%, yet we never observe sustained majority control. We evaluate the attack using the classical selfish mining model and a Markov-chain variant that captures Qubic's conservative release policy. At the inferred parameters, both models predict revenues below honest mining, and our measurements largely confirm this while showing systematic deviations. We attribute the gap to hashrate variability, coarse-grained interval detection, and operational frictions under community countermeasures. We further argue that selfish mining should be analyzed under time-varying hashrate. Even when the average hashrate stays below the static break-even point, an attacker can still run a profitable selfish-mining operation by operating it intermittently.

翻译：我们分析了Qubic于2025年公开宣称对门罗币发起的自私挖矿攻击。通过综合门罗币节点测量数据、Qubic矿池API及Qubic网络观测信息，我们重构了Qubic关联区块与有效算力，并识别出十个符合区块扣留与策略性释放特征的时段。在这些时段内，Qubic的平均算力占比升至23–34%，但我们从未观测到其持续占据多数控制权。我们使用经典自私挖矿模型及一个能捕捉Qubic保守释放策略的马尔可夫链变体对此次攻击进行评估。在推断参数下，两个模型均预测其收益低于诚实挖矿，而我们的测量数据在很大程度上证实了这一点，同时显示出系统性偏差。我们将此差异归因于算力波动性、粗粒度时段检测以及社区应对措施下的运营摩擦。我们进一步主张，自私挖矿应在时变算力条件下进行分析。即使平均算力低于静态盈亏平衡点，攻击者仍可通过间歇性操作运行盈利的自私挖矿活动。