Thousands of Twitter and Skype user account details have been found for sale on a Russian cyber black market.
Webroot researcher Dancho Danchev reported uncovering the nefarious scheme in a blog post on Wednesday, claiming the accounts details are of Russian users of numerous sites.
"Thousands of Russian Vkontakte, LiveJournal, Twitter, Mail.ru and Skype accounts are currently offered for sale, all of them active and valid," wrote Danchev.
"Based on the underground market advertisement, in 2012, the group/individual behind the service claims to have been in the possession of over 100 million accounting credentials, which have been obtained through ‘private methods'."
The black market is one of many to emerge in recent years. The markets generally sell everything from stolen financial and account information to exploit kits that can be used to mount automated cyber attacks.
The Webroot researcher warned criminals are developing new and sophisticated methods to power and monetise their activities.
"From compromised FTP credentials, CPanel accounts, portfolios of domains, to hacked PayPal and Steam accounts, cybercriminals are actively utilising compromised infrastructure as a foundation for the success of their fraudulent or malicious campaigns," wrote Danchev.
"Cybercriminals are applying quality assurance to their campaigns in terms of abusing the "chain of trust" established among owners of the compromised accounts and the prospective victims, in this case, their friends or colleagues."
Danchev said that the increased sophistication of the operations will lead to an increase in the number of active black markets.
"Thanks to the ease of generating or renting a partitioned botnet for your fraudulent and malicious needs, we predict a steady growth for this market segment," wrote Danchev.
Skype told V3 that it is aware of the threat, and urged users to be extra cautious with their details.
"We are aware of a claim of customer login credentials being made public, and as always, we encourage customers to keep their passwords secure. Customers can change their passwords,"said a Skype spokesperson.
The marketplace is one of many criminal operations to stem from Russia. The country is currently viewed as a hotbed for cybercrime.
Prior to Webroot's findings Trend Micro chief technology officer Raimund Genes listed Russian cyber criminals as one of the biggest threat facing businesses.
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