aspireai.
PUBLIC EDITION

BadTime pushed a backdoor trigger from 12 timesteps to 720 in multivariate time-series forecasting, cutting target MAE by 57 percent at a 1 percent poisoning rate

AspireAI community · arXiv
Multivariate long-term time-series forecasting runs in climate, finance and transportation, and the paper notes that its resistance to backdoor attacks had been entirely unexplored. BadTime is the first effective backdoor attack built for that setting. Two problems are specific to it: a local trigger dilutes fast over a long horizon, and the backdoor signal is extremely sparse under stealth constraints. The attack counters dilution with a distributed, lag-aware trigger that uses inter-variable correlations and temporal lags, and counters sparsity by mixing label-similar and label-dissimilar poisoned samples with a decoupled training objective that up-weights the sparse signal, which lets it work at a poisoning rate as low as 1 percent. Measured against the state-of-the-art time-series backdoor, it extended the attackable horizon from at most 12 timesteps to 720, a 60-fold improvement, reduced MAE on target variables by 57 percent on average, and changed average clean forecasting error by less than 1 percent.
Read the story and explore more from the AspireAI community.
Discover more stories
Stay curious.
THE BIG PICTURE
A FRESH PERSPECTIVE
Research
One distance function matched sparse-autoencoder features across layers and compressed feature circuits into supernodes
Two sparse-autoencoder analyses have resisted scaling: matching semantically similar features across layers, and compressing large feature circuits into interpretable supernodes. This paper argues both are the same underlying problem, estimating semantic distances between SAE features that sit on different activation manifolds. Its representation treats each feature not as a single decoder vector but as an activation-weighted distribution over the hidden states expressing it, projects those distributions into a shared reference space, and compares them with Wasserstein distance. The representation is proved invariant to activation rescaling and stable under perturbation, and recovers true matches under finite-sample margin conditions. Empirically it outperformed decoder-vector and LLM-based baselines and captured subtle functional distinctions between related features, and it compressed large feature circuits into interpretable supernodes automatically. The limitation is that this is interpretability tooling: the paper demonstrates better feature matching and circuit compression, not that downstream interpretability claims become more accurate.
Swipe into something new
01 / 1729
The conversation continues
Explore Builds — projects by Kiran Adimatyam ↗
A fresh perspective changes everything.
ASPIREAI — STAY CURIOUS.