Because the executable dates back to 2009-2010, modern antivirus software often quarantines wow repair.exe as a threat (Trojan:Win32/Wacatac). This is almost always a false positive.
In the era of World of Warcraft: Wrath of the Lich King (Patch 3.3.5), the utility was the primary way to fix corrupted game files before the modern Battle.net launcher existed. If you are playing on a private server or using an old client, here is how to use this classic tool to get back into Azeroth. What is Repair.exe? wow repair.exe 3.3.5