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