In 2269, Vulcan Security was called to the home of Ambassador Sarek after he was attacked by an assassin with an Ahn-Vahr. When they arrived, they believed that Spock had suffered a breakdown after suffering from amnesia that led to the loss of his knowledge of the Vulcan mind rules and attempted to kill his own father. They were later informed that Doctor Emma Saenz was a traitor working for the Romulan Star Empire leading to Vulcan Security Central attempting to locate her. (TOS novel: Mindshadow)
Spoiler warning: Plot and/or ending details follow.
In 2410, Chief Scientist Somat and his team of Vulcan researchers maintained a camp on planet Pahvo to study the Pahvans. They were protected by Vulcan Security Detail. When forces of the Terran Empire, led by Captain Sylvia Tilly of the ISS Discovery, conquered Pahvo, they incapacitated the Vulcans at the base camp. Somat returned with Alpha Quadrant Alliance reinforcements and treated the base team. A trio of Vulcan Security officers accompanied Somat and the Alliance away team while they attempted to undue the Terrans' modifications to Pahvo's ecosphere. After leaving the now evacuated camp and defeating Terran resistance, a rage-driven Pahvan appeared and projected its condition onto Somat and the Security detail. The Alliance team stunned the mind-controlled Vulcans, breaking the control. Somat surmised only his mental discipline would allow him to resist, and that the Alliance officers were safe because they had not been exposed as long to Pahvo as the Vulcans. The three Vulcan Security officers were beamed to safety, and Somat let the remaining team on. (STO - "Mirror of Discovery" mission: "Illusion of Communication")
In the early 25th century, officer of Vulcan Security wore a brown tunic with otherwise black slacks, boots and gloves. The tunic could be opened at the front. Just left to the chest, a silver IDIC pendant served as combadge. Above it, a black stripe had been placed. Clunky metallic devices sat above the waist, on the right arm, and the length of the left arm. Vulcan Security officers were armed with Starfleet-issue phaser rifles. (STO - "Mirror of Discovery" mission: "Illusion of Communication")