Thread Hijacking: Phishes That Prey on Your Curiosity

Thread hijacking attacks. They happen when someone you know has their email account compromised, and you are suddenly dropped into an existing conversation between the sender and someone else. These missives draw on the recipient’s natural curiosity about being copied on a private discussion, which is modified to include a malicious link or attachment. Here’s the story of a thread hijacking attack in which a journalist was copied on a phishing email from the unwilling subject of a recent scoop.

In Sept. 2023, the Pennsylvania news outlet LancasterOnline.com published a story about Adam Kidan, a wealthy businessman with a criminal past who is a major donor to Republican causes and candidates, including Rep. Lloyd Smucker (R-Pa).

The LancasterOnline story about Adam Kidan.

Several months after that piece ran, the story’s author Brett Sholtis received two emails from Kidan, both of which contained attachments. One of the messages appeared to be a lengthy conversation between Kidan and a colleague, with the subject line, “Re: Successfully sent data.” The second missive was a more brief email from Kidan with the subject, “Acknowledge New Work Order,” and a message that read simply, “Please find the attached.”

Sholtis said he clicked the attachment in one of the messages, which then launched a web page that looked exactly like a Microsoft Office 365 login page. An analysis of the webpage reveals it would check any submitted credentials at the real Microsoft website, and return an error if the user entered bogus account information. A successful login would record the submitted credentials and forward the victim to the real Microsoft website.

But Sholtis said he didn’t enter his Outlook username and password. Instead, he forwarded the messages to LancasterOneline’s IT team, which quickly flagged them as phishing attempts.

LancasterOnline Executive Editor Tom Murse said the two phishing messages from Mr. Kidan raised eyebrows in the newsroom because Kidan had threatened to sue the news outlet multiple times over Sholtis’s story.

“We were just perplexed,” Murse said. “It seemed to be a phishing attempt but we were confused why it would come from a prominent businessman we’ve written about. Our initial response was confusion, but we didn’t know what else to do with it other than to send it to the FBI.”

The phishing lure attached to the thread hijacking email from Mr. Kidan.

In 2006, Kidan was sentenced to 70 months in federal prison after pleading guilty to defrauding lenders along with Jack Abramoff, the disgraced lobbyist whose corruption became a symbol of the excesses of Washington influence peddling. He was paroled in 2009, and in 2014 moved his family to a home in Lancaster County, Pa.

The FBI hasn’t responded to LancasterOnline’s tip. Messages sent by KrebsOnSecurity to Kidan’s emails addresses were returned as blocked. Messages left with Mr. Kidan’s company, Empire Workforce Solutions, went unreturned.

No doubt the FBI saw the messages from Kidan for what they likely were: The result of Mr. Kidan having his Microsoft Outlook account compromised and used to send malicious email to people in his contacts list.

Thread hijacking attacks are hardly new, but that is mainly true because many Internet users still don’t know how to identify them. The email security firm Proofpoint says it has tracked north of 90 million malicious messages in the last five years that leverage this attack method.

One key reason thread hijacking is so successful is that these attacks generally do not include the tell that exposes most phishing scams: A fabricated sense of urgency. A majority of phishing threats warn of negative consequences should you fail to act quickly — such as an account suspension or an unauthorized high-dollar charge going through.

In contrast, thread hijacking campaigns tend to patiently prey on the natural curiosity of the recipient.

Ryan Kalember, chief strategy officer at Proofpoint, said probably the most ubiquitous examples of thread hijacking are “CEO fraud” or “business email compromise” scams, wherein employees are tricked by an email from a senior executive into wiring millions of dollars to fraudsters overseas.

But Kalember said these low-tech attacks can nevertheless be quite effective because they tend to catch people off-guard.

“It works because you feel like you’re suddenly included in an important conversation,” Kalember said. “It just registers a lot differently when people start reading, because you think you’re observing a private conversation between two different people.”

Some thread hijacking attacks actually involve multiple threat actors who are actively conversing while copying — but not addressing — the recipient.

“We call these multi-persona phishing scams, and they’re often paired with thread hijacking,” Kalember said. “It’s basically a way to build a little more affinity than just copying people on an email. And the longer the conversation goes on, the higher their success rate seems to be because some people start replying to the thread [and participating] psycho-socially.”

The best advice to sidestep phishing scams is to avoid clicking on links or attachments that arrive unbidden in emails, text messages and other mediums. If you’re unsure whether the message is legitimate, take a deep breath and visit the site or service in question manually — ideally, using a browser bookmark so as to avoid potential typosquatting sites.

Why is ‘Juice Jacking’ Suddenly Back in the News?

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.