RCS was the main tool sold by Hacking Team, which was founded in 2003. It enabled the extraction of files from a targeted device, interception of emails and instant messaging, and also remote activation of the webcam and microphone on a device.
Hacking Team was forced to ask its customers to suspend the use of RCS after about 400GB of its data was leaked.
In July 2016, a Cyprus-based company named Tablem bought 20% of Hacking Team's shares. Kafka cited reports that claim Tablem has ties to Saudi Arabia.
He said that input from Canada's Citizen Lab had helped ESET find other instances of RCS being used in the wild, all with slight modifications compared to the version which was being used before the breach.
An indicator that these versions were variants of the original RCS was the certificate used to sign them. "We found six different certificates issued in succession. Four of the certificates were issued by Thawte to four different companies, and two are personal certificates issued to Valeriano Bedeschi (Hacking Team co-founder) and someone named Raffaele Carnacina," Kafka wrote.
Another feature common with the pre-hack RCS was the use of VMProtect to make samples less easily detectable. A third common feature between the RCS of old and the samples found in wild was the versioning.
"The versioning (which we accessed after overcoming VMProtect protection) observed in the analysed samples continues where Hacking Team left off before the breach, and follows the same patterns," Kafka said.
"Hacking Team’s habit of compiling their payloads — named Scout and Soldier — consecutively, and often on the same day, can also be seen across the newer samples."
He said that further the post-breach updates of RCS following Hacking Team's coding style and were often found in places that reflected familiarity with the code.
One difference noticed between the pre-leak and post-leak versions of RCS was the size of the start-up file. "Before the leak, the copied file was padded to occupy 4MB. In the post-leak samples, this file copy operation is padded to 6MB – most likely as a primitive detection evasion technique," Kafka wrote.
He said the level of functionality in the post-leak RCS was the same as in the pre-leak version.
"As for the distribution vector of the post-leak samples we analysed, at least in two cases, we detected the spyware in an executable file disguised as a PDF document (using multiple file extensions) attached to a spearphishing email. The names of the attached files contain strings likely aimed to reduce suspicion when received by diplomats."
Kafka said ESET was not naming the countries where the port-leak version of RCS had been found "to prevent potentially incorrect attributions based on these detections, since the geo-location of the detections doesn’t necessarily reveal anything about the origin of the attack".