https://www.techtarget.com/searchsecurity/news/450418333/SS7-vulnerability-allows-attackers-to-drain-bank-accounts
A longtime vulnerability in Signaling System 7, the international telecommunications standard used by cellphone providers, helped attackers breach the accounts of bank customers in Germany.
Over the last few months, attackers used a security flaw in Signaling System 7, or SS7, to intercept two-factor authentication codes sent to online banking customers trying to transfer money. The German newspaper Süddeutsche Zeitung reported that the attackers first compromised the bank accounts of customers using traditional bank fraud Trojans to steal passwords and log into the accounts. They then used the SS7 vulnerability to redirect text messages containing one-time passwords to attackers' devices instead of customers. They then used mobile transaction authentication numbers (mTANs) to transfer money out of the targeted accounts.
A representative from O2 Telefonica, an affected telecom in Germany, confirmed the attacks to Süddeutsche Zeitung stating that, "criminals carried out an attack from a network of a foreign mobile network operator in the middle of January. The attack redirected incoming SMS messages for selected German customers to the attackers."
This SS7 vulnerability is not new; it was first discovered by German researchers in 2014 and reported by The Washington Post.
The discovery of this abuse of the SS7 vulnerability follows an open letter two U.S. congressmen wrote to U.S. Homeland Security Secretary John Kelly asking both for an update on the progress in dealing with SS7 security flaws and why the agency isn't doing more about it.
One of the authors behind the letter, Rep. Ted Lieu (D-Calif.), has firsthand experience with the SS7 vulnerability. With Lieu's permission, security researchers were able to essentially stalk the congressman using only his cellphone number and an SS7 network. The researchers were able to record his phone calls and monitor his exact location in real time. The exploit of Lieu's cellphone was featured on the television show 60 Minutes, and following its airing in April 2016, the FCC opened an investigation into the SS7 vulnerability. A report from the FCC was expected in March 2016, but has yet to appear.
In response to the draining of bank accounts using the same SS7 vulnerability, Lieu issued a statement calling for congressional action on the matter.
"Everyone's accounts protected by text-based two-factor authentication, such as bank accounts, are potentially at risk until the FCC and telecom industry fix the devastating SS7 security flaw," Lieu said. "Both the FCC and telecom industry have been aware that hackers can acquire our text messages and phone conversations just knowing our cellphone number. It is unacceptable the FCC and telecom industry have not acted sooner to protect our privacy and financial security. I urge the Republican-controlled Congress to hold immediate hearings on this issue."
05 May 2017