It depends. With some code, especially in some games, it can be misidentified as a virus due to the fact it is similar to a virus' code, marking it as a virus or trojan. On top of this, some malicious uploaders put viruses or trojans into your download, so that, when you run it, it activates the malicious code. Other times they are false-positives, where the anti-virus program flags it as a virus when there is nothing wrong with it.
Lots of cracks have hidden agenda. Some of them include trojans to pay for the development of the crack. Some of them provide backdoor access to the crack developer.
Any program that modifies other programs or is packed with various code-hiding techniques is suspicious. That is extremely common for keygens, cracks and other similar programs, and that is detected by antiviruses. This approach helps in detecting fresh viruses that have not landed in antivirus databases yet.
They will often have information from game companies about the file signature the game should have. If the file doesn't match the signature, then it marks the file as being compromised (PUPs (Potentially unwanted programs) )-- because, well, it has, even if you're the one who intentionally compromised it with the crack.
cracks are tampered files , nothing less than a trojan to make u break into a game'd DRM to play without the DVD
Will they harm u ?
if u are downloading from an untrusted uploader or website , yes it but ET is the place to be , mods here test PC games and trusted uploaders are uploading great games here
For your info , the game exe and steam_api.dll is the crack mostly for steam games
just to be extra secure , people prefer more to download game from SCENE release group which gets uploaded here instead of repacks , people who have a fast net as SCENE are often twice ot thrice the size of a pc repack , SCENE release groups are always trusted and are original crackers of the game
look for their tags , some common Scene groups are :
RELOADED , CODEX , SKIDROW , CONSPIRACY (CPY) , ALI213 , ViTalITY , RAZOR1911 ,PROPHET , PLAZA , HI2U
if u see any of these tags , u can be assured of quality
in repacks , always check in the description for the crack/tablet its based on ,
there is one another cracker , 3DM which ain't a part of SCENE warez group but is still trustable , hope it helps !!