Global mobile roaming network a HOTBED of vulnerabilities

KPN researchers find more than 5k vulnerable hosts

Security experts for Dutch telco KPN have swung the baseball bat at telcos, with research suggesting mobile roaming networks are so insecure you'd hardly need the NSA to break in and start capturing user traffic.

They find the GRX – GPRS Roaming Exchange – network, which links the roaming traffic of 25 carriers worldwide, has more than 5,000 vulnerable hosts visible to the Internet.

That roaming network is the same as the UK's GCHQ targeted, via Belgacom engineers, to capture traffic.

It would, it seems, have been easier and cheaper to just attack Internet-exposed GRX hosts directly, according to KPN penetration tester Stephen Kho and incident response handler Rob Kuiters.

They found that of the 25 operators, 15 have machines visible to the Internet, with many misconfigurations and unnecessary services, and a lack of ingress filtering to protect the hosts.

The problem is one that's repeated many times the world over: something that's designed to only be a private network with trusted connections gets connected to the Internet, deliberately or accidentally, and security hell breaks loose.

In the case of GRX, the issue is that roaming is a concept that existed long before carriers started offering mobile Internet services. The latter demand a gateway between the Internet and the mobile network, and a careless carrier might also expose its GRX hosts to the Internet.

In this presentation to Haxpo in the Netherlands, the researchers note that if an attacker has access to GTP (the GPRS Tunnelling Protocol) traffic, user privacy is out the window: who communicated what is sniffable.

What the research found was that out of 42,000 GRX hosts, around 5,500 are visible from the Internet, and many of these are running services with known vulnerabilities, including various old Sendmail versions with known root exploits, and vulnerable ftpd daemons in OpenBSD, VxWorks, and other FTP implementations.

There's also vulnerable Web server versions from Apache, Microsoft and Oracle – as they note, “why are these servers even here?” – several problematic telnets, and so on. Once they spot systems like Windows 2000 LAN Manager and the vulnerable Samba 3.6.3, they say, it “looks like people are mixing GRX and [their] office network!”

Vulnerable kit from Cisco, Huawei, Ericsson and others also turned out to be reachable from the Internet, they claimed.

The responsible operators have been notified, the researchers say.

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