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KrebsOnSecurity received a nice bump in traffic this week thanks to tweets from the Federal Bureau of Investigation (FBI) and the Federal Communications Commission (FCC) about “juice jacking,” a term first coined here in 2011 to describe a potential threat of data theft when one plugs their mobile device into a public charging kiosk. It remains unclear what may have prompted the alerts, but the good news is that there are some fairly basic things you can do to avoid having to worry about juice jacking.
On April 6, 2023, the FBI’s Denver office issued a warning about juice jacking in a tweet.
“Avoid using free charging stations in airports, hotels or shopping centers,” the FBI’s Denver office warned. “Bad actors have figured out ways to use public USB ports to introduce malware and monitoring software onto devices. Carry your own charger and USB cord and use an electrical outlet instead.”
Five days later, the Federal Communications Commission (FCC) issued a similar warning. “Think twice before using public charging stations,” the FCC tweeted. “Hackers could be waiting to gain access to your personal information by installing malware and monitoring software to your devices. This scam is referred to as juice jacking.”
The FCC tweet also provided a link to the agency’s awareness page on juice jacking, which was originally published in advance of the Thanksgiving Holiday in 2019 but was updated in 2021 and then again shortly after the FBI’s tweet was picked up by the news media. The alerts were so broadly and breathlessly covered in the press that a mention of juice jacking even made it into this week’s Late Late Show with James Corden.
The term juice jacking crept into the collective paranoia of gadget geeks in the summer of 2011, thanks to the headline for a story here about researchers at the DEFCON hacker convention in Vegas who’d set up a mobile charging station designed to educate the unwary to the reality that many mobile devices connected to a computer would sync their data by default.
Since then, Apple, Google and other mobile device makers have changed the way their hardware and software works so that their devices no longer automatically sync data when one plugs them into a computer with a USB charging cable. Instead, users are presented with a prompt asking if they wish to trust a connected computer before any data transfer can take place.
On the other hand, the technology needed to conduct a sneaky juice jacking attack has become far more miniaturized, accessible and cheap. And there are now several products anyone can buy that are custom-built to enable juice jacking attacks.
Probably the best known example is the OMG cable, a $180 hacking device made for professional penetration testers that looks more or less like an Apple or generic USB charging cable. But inside the OMG cable is a tiny memory chip and a Wi-Fi transmitter that creates a Wi-Fi hotspot, to which the attacker can remotely connect using a smartphone app and run commands on the device.
The $180 “OMG cable.” Image: hak5.org.
Brian Markus is co-founder of Aries Security, and one of the researchers who originally showcased the threat from juice jacking at the 2011 DEFCON. Markus said he isn’t aware of any public accounts of juice jacking kiosks being found in the wild, and said he’s unsure what prompted the recent FBI alert.
But Markus said juice jacking is still a risk because it is far easier and cheaper these days for would-be attackers to source and build the necessary equipment.
“Since then, the technology and components have become much smaller and very easy to build, which puts this in the hands of less sophisticated threat actors,” Markus said. “Also, you can now buy all this stuff over the counter. I think the risk is possibly higher now than it was a decade ago, because a much larger population of people can now pull this off easily.”
How seriously should we take the recent FBI warning? An investigation by the myth-busting site Snopes suggests the FBI tweet was just a public service announcement based on a dated advisory. Snopes reached out to both the FBI and the FCC to request data about how widespread the threat of juice jacking is in 2023.
“The FBI replied that its tweet was a ‘standard PSA-type post’ that stemmed from the FCC warning,” Snopes reported. “An FCC spokesperson told Snopes that the commission wanted to make sure that their advisory on “juice-jacking,” first issued in 2019 and later updated in 2021, was up-to-date so as to ensure ‘the consumers have the most up-to-date information.’ The official, who requested anonymity, added that they had not seen any rise in instances of consumer complaints about juice-jacking.”
What can you do to avoid juice jacking? Bring your own gear. A general rule of thumb in security is that if an adversary has physical access to your device, you can no longer trust the security or integrity of that device. This also goes for things that plug into your devices.
Juice jacking isn’t possible if a device is charged via a trusted AC adapter, battery backup device, or through a USB cable with only power wires and no data wires present. If you lack these things in a bind and still need to use a public charging kiosk or random computer, at least power your device off before plugging it in.
The Department of Homeland Security (DHS) is urging states and localities to beef up security around proprietary devices that connect to the Emergency Alert System — a national public warning system used to deliver important emergency information, such as severe weather and AMBER alerts. The DHS warning came in advance of a workshop to be held this weekend at the DEFCON security conference in Las Vegas, where a security researcher is slated to demonstrate multiple weaknesses in the nationwide alert system.
A Digital Alert Systems EAS encoder/decoder that Pyle said he acquired off eBay in 2019. It had the username and password for the system printed on the machine.
The DHS warning was prompted by security researcher Ken Pyle, a partner at security firm Cybir. Pyle said he started acquiring old EAS equipment off of eBay in 2019, and that he quickly identified a number of serious security vulnerabilities in a device that is broadly used by states and localities to encode and decode EAS alert signals.
“I found all kinds of problems back then, and reported it to the DHS, FBI and the manufacturer,” Pyle said in an interview with KrebsOnSecurity. “But nothing ever happened. I decided I wasn’t going to tell anyone about it yet because I wanted to give people time to fix it.”
Pyle said he took up the research again in earnest after an angry mob stormed the U.S. Capitol on Jan. 6, 2021.
“I was sitting there thinking, ‘Holy shit, someone could start a civil war with this thing,”’ Pyle recalled. “I went back to see if this was still a problem, and it turns out it’s still a very big problem. So I decided that unless someone actually makes this public and talks about it, clearly nothing is going to be done about it.”
The EAS encoder/decoder devices Pyle acquired were made by Lyndonville, NY-based Digital Alert Systems (formerly Monroe Electronics, Inc.), which issued a security advisory this month saying it released patches in 2019 to fix the flaws reported by Pyle, but that some customers are still running outdated versions of the device’s firmware. That may be because the patches were included in version 4 of the firmware for the EAS devices, and many older models apparently do not support the new software.
“The vulnerabilities identified present a potentially serious risk, and we believe both were addressed in software updates issued beginning Oct 2019,” EAS said in a written statement. “We also provided attribution for the researcher’s responsible disclosure, allowing us to rectify the matters before making any public statements. We are aware that some users have not taken corrective actions and updated their software and should immediately take action to update the latest software version to ensure they are not at risk. Anything lower than version 4.1 should be updated immediately. On July 20, 2022, the researcher referred to other potential issues, and we trust the researcher will provide more detail. We will evaluate and work to issue any necessary mitigations as quickly as possible.”
But Pyle said a great many EAS stakeholders are still ignoring basic advice from the manufacturer, such as changing default passwords and placing the devices behind a firewall, not directly exposing them to the Internet, and restricting access only to trusted hosts and networks.
Pyle, in a selfie that is heavily redacted because the EAS device behind him had its user credentials printed on the lid.
Pyle said the biggest threat to the security of the EAS is that an attacker would only need to compromise a single EAS station to send out alerts locally that can be picked up by other EAS systems and retransmitted across the nation.
“The process for alerts is automated in most cases, hence, obtaining access to a device will allow you to pivot around,” he said. “There’s no centralized control of the EAS because these devices are designed such that someone locally can issue an alert, but there’s no central control over whether I am the one person who can send or whatever. If you are a local operator, you can send out nationwide alerts. That’s how easy it is to do this.”
One of the Digital Alert Systems devices Pyle sourced from an electronics recycler earlier this year was non-functioning, but whoever discarded it neglected to wipe the hard drive embedded in the machine. Pyle soon discovered the device contained the private cryptographic keys and other credentials needed to send alerts through Comcast, the nation’s third-largest cable company.
“I can issue and create my own alert here, which has all the valid checks or whatever for being a real alert station,” Pyle said in an interview earlier this month. “I can create a message that will start propagating through the EAS.”
Comcast told KrebsOnSecurity that “a third-party device used to deliver EAS alerts was lost in transit by a trusted shipping provider between two Comcast locations and subsequently obtained by a cybersecurity researcher.
“We’ve conducted a thorough investigation of this matter and have determined that no customer data, and no sensitive Comcast data, were compromised,” Comcast spokesperson David McGuire said.
The company said it also confirmed that the information included on the device can no longer be used to send false messages to Comcast customers or used to compromise devices within Comcast’s network, including EAS devices.
“We are taking steps to further ensure secure transfer of such devices going forward,” McGuire said. “Separately, we have conducted a thorough audit of all EAS devices on our network and confirmed that they are updated with currently available patches and are therefore not vulnerable to recently reported security issues. We’re grateful for the responsible disclosure and to the security research community for continuing to engage and share information with our teams to make our products and technologies ever more secure. Mr. Pyle informed us promptly of his research and worked with us as we took steps to validate his findings and ensure the security of our systems.”
The user interface for an EAS device.
Unauthorized EAS broadcast alerts have happened enough that there is a chronicle of EAS compromises over at fandom.com. Thankfully, most of these incidents have involved fairly obvious hoaxes.
According to the EAS wiki, in February 2013, hackers broke into the EAS networks in Great Falls, Mt. and Marquette, Mich. to broadcast an alert that zombies had risen from their graves in several counties. In Feb. 2017, an EAS station in Indiana also was hacked, with the intruders playing the same “zombies and dead bodies” audio from the 2013 incidents.
“On February 20 and February 21, 2020, Wave Broadband’s EASyCAP equipment was hacked due to the equipment’s default password not being changed,” the Wiki states. “Four alerts were broadcasted, two of which consisted of a Radiological Hazard Warning and a Required Monthly Test playing parts of the Hip Hop song Hot by artist Young Thug.”
In January 2018, Hawaii sent out an alert to cell phones, televisions and radios, warning everyone in the state that a missile was headed their way. It took 38 minutes for Hawaii to let people know the alert was a misfire, and that a draft alert was inadvertently sent. The news video clip below about the 2018 event in Hawaii does a good job of walking through how the EAS works.
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