The most severe danger stems from the tools themselves. Users are often directed to download cracked software, third-party video downloaders, or browser extensions from unverified sources. This is a primary vector for malware distribution. Security researchers have found that "the NullMixer dropper can run many instances of malware all at once, and more than half of them are malicious downloaders". It is not uncommon for tools advertised as video downloaders to be bundled with spyware, adware, or even ransomware.