Valve eventually patched the loopholes that allowed these generic cracks to hijack their matchmaking lobbies.
A modified left4dead2.exe to stop the game from checking digital signatures. l4d2-fix-repair-steam-v3-generic-rar
Valve frequently puts Left 4 Dead 2 on sale for as low as $0.99, making the risk of downloading a sketchy 15-megabyte fix file completely illogical. Valve eventually patched the loopholes that allowed these
A modified configuration file that forced the game to search for lobbies on private, cracked master servers rather than Valve's official ones. l4d2-fix-repair-steam-v3-generic-rar