On Wednesday, large chunks of network traffic belonging to MasterCard, Visa, and more than two dozen other financial services companies were briefly routed through a Russian government-controlled telecom under unexplained circumstances that renew lingering questions about the trust and reliability of some of the most sensitive Internet communications.

Anomalies in the border gateway protocol—which routes large-scale amounts of traffic among Internet backbones, ISPs, and other large networks—are common and usually the result of human error. While it's possible Wednesday's five- to seven-minute hijack of 36 large network blocks may also have been inadvertent, the high concentration of technology and financial services companies affected made the incident "curious" to engineers at network monitoring service BGPmon. What's more, the way some of the affected networks were redirected indicated their underlying prefixes had been manually inserted into BGP tables, most likely by someone at Rostelecom, the Russian government-controlled telecom that improperly announced ownership of the blocks.
"Quite suspicious"

"I would classify this as quite suspicious," Doug Madory, director of Internet analysis at network management firm Dyn, told Ars. "Typically accidental leaks appear more voluminous and indiscriminate. This would appear to be targeted to financial institutions. A typical cause of these errors [is] in some sort of internal traffic engineering, but it would seem strange that someone would limit their traffic engineering to mostly financial networks."

Normally, the network traffic bound for MasterCard, Visa, and the other affected companies passes through services providers that the companies hire and authorize. Using BGP routing tables, the authorized providers "announce" their ownership of the large blocks of IP addresses belonging to the client companies. On Wednesday afternoon at around 3:36pm Pacific time, however, Rostelecom suddenly announced its control of the blocks. As a result, traffic flowing into the affected networks started passing through Rostelecom's routers. The hijacking lasted five to seven minutes. When it was over, normal routing was restored. The event is nicely captured in a graphic here.

The hijacking could have allowed individuals in Russia to intercept or manipulate traffic flowing into the affected address space. Such interception or manipulation would be most easily done to data that wasn't encrypted, but even in cases when it was encrypted, traffic might still be decrypted using attacks with names such as Logjam and DROWN, which work against outdated transport layer security implementations that some organizations still use.