A Call of Duty: Modern Warfare player has shown off a rather efficient way to score multiple kills at a time in the Infected game mode. All they had to do was stab their Survivor teammates in the back with an Airstrike Killstreak.
Cache B78 displayed the exploit in the Modern Warfare subreddit. While standing on a roof with the majority of his Survivor teammates, Cache quickly and secretly called in an airstrike. Something like this would usually be harmless, as Infected doesn't have friendly fire enabled, meaning players can't kill their own teammates. However, since Cache was on a tall building, all they had to do to solve this problem was jump off.
As soon as their body hit the ground, Cache became a member of the Infected team, and the friendly fire protection their old comrades had was nullified. Thus, when the airstrike made it to the roof, it pretty much wiped them all out. In the end, Cache ended up with over 13 kills.
Cache isn't the first person to do this in Infected, either. Many players are starting to realize they can steal several kills by just using a delayed Killstreak on their huddled together team before killing themselves. The trick is consistent because the typical strategy Survivors use clusters them together once the game nears its climax. It's much easier for the group to get overrun by infected if they don't.
So since Survivors can no longer trust their partners not to kill them while dealing with hordes, some players are requesting for Infinity Ward to make a change, and they've even thrown in some suggestions as to what can be done. The simplest and most likely proposal, however, was to just keep friendly fire disabled.
Players can only pull off the exploit while they're still on the Survivor team, so making their Killstreak retain its friendly fire properties — even if the player dies — makes the most the sense. It also prevents any accidents a player might have, such as using a Killstreak near their team in an attempt to stave off a horde only to end up dying and taking the rest of their members down with them.
As of this writing, Infinity Ward hasn't addressed the exploit, though that will probably change soon with the way it's picking up steam.
Call of Duty: Modern Warfare is available now on PC, PS4, and Xbox One.