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, (PDF) released Thursday, 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.

The report comes nearly a year after the first disclosures from NSA whistleblower Edward Snowden elevated privacy into the mainstream debate.

"In the face of unbounded surveillance, users of technology need to know which companies are willing to take a stand for the privacy of their users," the report said.

It added that the study's findings are "to allow users to make informed decisions about the companies with whom they do business. It is also designed to incentivize companies to adopt best practices, be transparent about how data flows to the government, and to take a stand for their users' privacy in Congress and the courts whenever it is possible to do so."

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."

Perhaps the most controversial category the EFF examined is whether companies require warrants for customer data stored on their servers. For the most part, federal law adopted in the President Ronald Reagan era does not require a warrant, but a federal appeals court said in 2010 that a warrant was required.

Congress has failed to act despite repeatedly promising that accessing content stored on third-party servers would require warrants, the same standard needed to seize old-school papers and effects.

That has left the Fourth Amendment in the hands of a hodgepodge of varying policies by tech companies. Comcast, AT&T, and Snapchat were the only three companies failing to earn stars in the warrant-requirement category.