  Detecting active black holes in dwarf galaxies has proven to be a challenge
due to their small size and weak electromagnetic signatures. Mid-infrared
variability has emerged as a promising tool that can be used to detect active
low-mass black holes in dwarf galaxies. We analyzed 10.4 years of photometry
from the ALL$WISE$/NEO$WISE$ multi-epoch catalogs, identifying 25 objects with
AGN-like variability. Independent confirmation of AGN activity was found in 68%
of these objects using optical and near-infrared diagnostics. Notably, we
discovered a near-infrared coronal line [S IX] $\lambda$ 1.252 $\mu$m in J1205,
the galaxy with the lowest stellar mass (log M$_{*}$ = 7.5 M$_{\odot}$) and low
metallicity (12 + log(O/H) = 7.46) in our sample. Additionally, we found broad
Pa$\alpha$ potentially from the BLR in two targets, and their implied black
hole masses are consistent with black hole-stellar mass relations. Comparing
non-variable galaxies with similar stellar masses and $WISE$ $W1-W2$ colors, we
found no clear trends between variability and large-scale galaxy properties.
However, we found that AGN activity likely causes redder $W1-W2$ colors in
variable targets, while for the non-variable galaxies, the contribution stems
from strong star formation activity. A high incidence of optical broad lines
was also observed in variable targets. Our results suggest that mid-infrared
variability is an effective method for detecting AGN activity in low-mass
galaxies and can help uncover a larger sample of active low-mass ($<$ 10$^{6}$
M$_{\odot}$) black holes in the universe.
