A security researcher described the incident as a "very critical data breach, making every T-Mobile cell phone owner a victim".
The hackers used specialised malware to leave no trace of their activities, their "tradecraft" suggesting involvement with an organised cybercrime group.
The malware has been sold in underground hacking forums with prices ranging from $29 a week to $299 for a full-package "pro" deal.
The attack allows hackers to infiltrate firms' Office 365 accounts by attempting to "knock" on backdoor system accounts.
Millions of internet users in the US, Canada, UK and Australia were recently targeted by a hacking group called KovCoreG which took advantage of PornHub to spread adware.
There is no evidence to suggest that confidential client and employee data, as well as financial information, were accessed.
Researchers said this technique has already been used to infiltrate the networks of a Middle Eastern bank and also of "individuals with indirect ties to a country in North East Asia".
The interconnected security camera was reportedly purchased by the woman so that she could keep an eye on her dog while she was away.
"While we are still investigating the incident, we believe that it is best to share what we know now," Disqus' chief technology officer Jason Yan said.
Hacking targets included former Central Intelligence Agency director John Brennan and former deputy director of the Federal Bureau of Investigation Mark Giuliano.
US intelligence believes that at least two Moscow-linked hacking groups targeted American institutions in order to help spread misinformation and propaganda last year.
The Finans allegedly stole consumer electronics including GoPro digital cameras, Microsoft Xboxes, Samsung smartwatches, and Microsoft Surface tablets from Amazon.
Russia is also seeking alleged cybercriminal Alexander Vinnik's extradition on separate fraud charges, but no date has yet been set for that hearing.
Hackers stole a trove of valuable personal and financial details in the record-breaking data breach.
The spoof emails impersonate legitimate banking institutions such as Bank of America to trick unsuspecting victims.
"If I go to the US, I will die in a year," Levashov, who is fighting extradition to the US, was quoted as saying.
Whole Foods is the latest in a series of major US chains to have suffered a data breach.
Fake 'likes' can amplify content on social media and skew search results.
A total of 6.7m bots joined the global botnet in 2016, claims cybersecurity firm Symantec.
Physical access to ATMs is no longer needed to hijack cash, experts warn.
The malware was detected in over 40 countries and is being spread through over 1,200 malicious Android apps.
Passwords and account details could be put at risk by weak app cybersecurity.