Here is the full list of all 27 Call of Duty: Modern Warfare achievements.
Complete all Special Operations missions.
Kill all enemies at the Church, Clocktower, and Pool without anyone calling for backup.
Kill at least one enemy while inside The Reading Place, Aural Chic, and both Subway undergrounds.
Kill an enemy with a direct hit from a smoke grenade.
Burn 4 enemies with a single molotov.
Take down a flying helicopter with a molotov.
Complete 'Clean House' without being hit using one bullet per threat.
Kill both soldiers with one shot in 'Hometown'.
Save Alpha 3-2 from being downed.
Never get hit by the sniper while escaping captivity.
Spit on Barkov.
Complete 'The Wolf's Den' tunnels using only the 1911.
Kill 3 enemies while you are on a ladder.
Blow up 3 tripwires with explosives.
Reach Barkov's lab entrance using only drone strikes.
Shut off the power to 4 buildings in 'Going Dark'.
Get at least one kill with eight different weapons when completing 'Old Comrades'.
Only use one cinder block and bring it to the end of 'Embedded'.
Kill all the enemies in the 'Embedded' field of dead bodies.
Neutralize the 'Fog of War' machine gun with a frag grenade.
Do not injure any civilians in 'Piccadilly'.
Complete every single player mission on Veteran or Realism difficulty.
Finish single player on any difficulty.
Stop three APCs with Hadir's sniper rifle.
Shoot the driver of the suicide truck.
Destroy 4 trucks with 4 drone strikes before they reach the end of their path in 'The Embassy'.
Crash a helicopter by shooting the pilot.