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0-Day Vulnerability Exposes Thousands Of AT&T Broadband Customers To Attack

AT&T and hardware manufacturer Arris are being accused of leaving millions of broadband subscribers open to attack. A new report by security researcher Joseph Hutchins highlights how five flaws were discovered in Arris routers used by AT&T and numerous other ISPs around the world. Hutchins notes that some of the flaws may have been introduced after they were delivered to AT&T, since ISPs traditionally modify hardware for use on their network post sale. But many of the flaws were courtesy of the all-too-common tendency to ship hardware with hardcoded credentials and SSH enabled by default:

"It was found that the latest firmware update (9.2.2h0d83) for the NVG589 and NVG599 modems enabled SSH and contained hardcoded credentials which can be used to gain access to the modem’s “cshell” client over SSH. The cshell is a limited menu driven shell which is capable of viewing/changing the WiFi SSID/password, modifying the network setup, re-flashing the firmware from a file served by any tftp server on the Internet, and even controlling what appears to be a kernel module whose sole purpose seems to be to inject advertisements into the user’s unencrypted web traffic."

Nearly 140,000 devices are impacted, and the Arris NVG589 and NVG599 modems are used by AT&T to power its VDSL broadband (formerly U-verse) service. The vulnerabilities not only open up subscribers to attack, but hardcoded credentials are also to thank for the rise in historically massive DDoS attacks as malware targets such devices for use in botnets. In addition to hard-coded credentials (which you'd think any sensible hardware vendor would steer well clear of at this point), Hutchins notes the devices suffer from default https server credentials, command injection vulnerabilities, and a a firewall bypass on port 49152.

AT&T is refusing to comment and Arris tells ThreatPost it's looking into the flaws. Whichever party is to blame, Hutchins noted that the vulnerability was a result of "pure carelessness" at the companies:

"Regardless of why, when, or even who introduced these vulnerabilities, it is the responsibility of the ISP to ensure that their network and equipment are providing a safe environment for their end users. This, sadly, is not currently the case. The first vulnerability found was caused pure carelessness, if not intentional all together. Furthermore, it is hard to believe that no one is already exploiting this vulnerability at the detriment of innocents."

At a recent Defcon, hackers demonstrated how they were able to break into around half of thirty different commercially-available residential broadband routers without too much elbow grease. Why does this continue to be such a problem? Security experts like Bruce Schneier have repeatedly noted how the same flimsy security we enjoy mocking in the internet of broken things space is all too present in residential broadband router market, thanks in large part to nobody in the supply chain having the financial incentive to do much about it:

"Typically, these systems are powered by specialized computer chips made by companies such as Broadcom, Qualcomm, and Marvell. These chips are cheap, and the profit margins slim. Aside from price, the way the manufacturers differentiate themselves from each other is by features and bandwidth. They typically put a version of the Linux operating system onto the chips, as well as a bunch of other open-source and proprietary components and drivers. They do as little engineering as possible before shipping, and there’s little incentive to update their “board support package” until absolutely necessary.

The system manufacturers – usually original device manufacturers (ODMs) who often don't get their brand name on the finished product – choose a chip based on price and features, and then build a router, server, or whatever. They don't do a lot of engineering, either. The brand-name company on the box may add a user interface and maybe some new features, make sure everything works, and they're done, too."

After that, everybody in the cycle is too focused on making money on the next product or chipset to do the legwork required to keep the hardware or software in these devices updated or secure. This is at the heart of IOT dysfunction, but the problem goes notably deeper than just your easily hacked smart thermostat. Fair or not, the onus then gets put in the lap of the broadband ISP -- since they field the support calls once a customer gets hacked. But swapping out the hardware or troubleshooting existing gear erodes profit margins as well -- at companies that already cut customer support corners to an often comical degree.

As script-kiddie oriented malware kits make attacking these vulnerabilities easier than ever, the problem nobody seems to want to fix is going to only get worse. And while some might incorrectly call it hyperbole, that's why Schneier and many other security researchers have been warning for years that there's dumpster fire just over the horizon that could result in a notable loss of human lives. It's a future everybody in the space can pretty clearly see, but few are willing to spend the money to avoid.



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