  Adversarial attacks on thermal infrared imaging expose the risk of related
applications. Estimating the security of these systems is essential for safely
deploying them in the real world. In many cases, realizing the attacks in the
physical space requires elaborate special perturbations. These solutions are
often \emph{impractical} and \emph{attention-grabbing}. To address the need for
a physically practical and stealthy adversarial attack, we introduce
\textsc{HotCold} Block, a novel physical attack for infrared detectors that
hide persons utilizing the wearable Warming Paste and Cooling Paste. By
attaching these readily available temperature-controlled materials to the body,
\textsc{HotCold} Block evades human eyes efficiently. Moreover, unlike existing
methods that build adversarial patches with complex texture and structure
features, \textsc{HotCold} Block utilizes an SSP-oriented adversarial
optimization algorithm that enables attacks with pure color blocks and explores
the influence of size, shape, and position on attack performance. Extensive
experimental results in both digital and physical environments demonstrate the
performance of our proposed \textsc{HotCold} Block. \emph{Code is available:
\textcolor{magenta}{https://github.com/weihui1308/HOTCOLDBlock}}.
