AT&T, Comcast, and Snapchat are laggards on privacy policies

The results are in on the Electronic Frontier Foundation's fourth annual "Who Has Your Back" report on the tech sector's customer privacy practices.

The highest ratings -- companies given six stars -- were handed to Apple, Credo Mobile, Dropbox, Facebook, Google, Microsoft, Sonic, Twitter, and Yahoo.

The report reviewed 26 companies in all, rating them on everything from whether they require warrants for data handovers to whether they have publicly opposed mass surveillance and fight for "users' privacy rights in courts."

The study found that Snapchat, AT&T, and Comcast lagged "behind others." Snapchat was among the biggest privacy underachievers, earning one star. "This is particularly troubling because Snapchat collects extremely sensitive user data, including potentially compromising photographs of users. Given the large number of users and non users whose photos end up on Snapchat, Snapchat should publicly commit to requiring a warrant before turning over the content of its users’ communications to law enforcement," said the 73-page analysis.

However, the digital rights group cautioned that the report has a major shortcoming: "The categories we evaluate in this report represent objectively verifiable, public criteria and so cannot and do not evaluate secret surveillance."