The Rabbit Mask is a seasonal item in RUST released during the Lunar New Year event in January of 2023.
Alongside the Dragon Door Knocker and Chinese Lantern, this is a limited-time purchase available from the in-game RUST store during the week of the Lunar New Year. It is discontinued afterward and available only for trade on the steam marketplace.
From a statistically functional perspective, the rabbit mask is a basic reskin of the Wolf Headdress, complete with the same cost and defensive capacity. Unlike said headdress, it crafts considerably faster when not under the effect of any tier workbench. When paired with the Bandana Mask, it provides projectile protection equal to the Coffee Can Helmet.
The only way to acquire this item in-game aside from Administrative F1 Console spawning is to own the steam item and craft it or by trading for it from someone who crafted it.
Its unique appearance makes the wearer resemble a person wearing a huge bunny rabbit face on their head, topped off with decorative bangles, becoming carrot-carnage-incarnate and striking fear into the hearts of vegetarians everywhere.