Two Charged in SIM Swapping, Vishing Scams
Two young men from the eastern United States have been hit with identity theft and conspiracy charges for allegedly stealing bitcoin and social media accounts by tricking employees at wireless phone companies into giving away credentials needed to remotely access and modify customer account information.
Prosecutors say Jordan K. Milleson, 21 of Timonium, Md. and 19-year-old Kingston, Pa. resident Kyell A. Bryan hijacked social media and bitcoin accounts using a mix of voice phishing or “vishing” attacks and “SIM swapping,” a form of fraud that involves bribing or tricking employees at mobile phone companies.
Investigators allege the duo set up phishing websites that mimicked legitimate employee portals belonging to wireless providers, and then emailed and/or called employees at these providers in a bid to trick them into logging in at these fake portals.
According to the indictment (PDF), Milleson and Bryan used their phished access to wireless company employee tools to reassign the subscriber identity module (SIM) tied to a target’s mobile device. A SIM card is a small, removable smart chip in mobile phones that links the device to the customer’s phone number, and their purloined access to employee tools meant they could reassign any customer’s phone number to a SIM card in a mobile device they controlled.
That allowed them to seize control over a target’s incoming phone calls and text messages, which were used to reset the password for email, social media and cryptocurrency accounts tied to those numbers.
Interestingly, the conspiracy appears to have unraveled over a business dispute between the two men. Prosecutors say on June 26, 2019, “Bryan called the Baltimore County Police Department and falsely reported that he, purporting to be a resident of the Milleson family residence, had shot his father at the residence.”
“During the call, Bryan, posing as the purported shooter, threatened to shoot himself and to shoot at police officers if they attempted to confront him,” reads a statement from the U.S. Attorney’s Office for the District of Maryland. “The call was a ‘swatting’ attack, a criminal harassment tactic in which a person places a false call to authorities that will trigger a police or special weapons and tactics (SWAT) team response — thereby causing a life-threatening situation.”
The indictment alleges Bryan swatted his alleged partner in retaliation for Milleson failing to share the proceeds of a digital currency theft. Milleson and Bryan are facing charges of wire fraud, unauthorized access to protected computers, aggravated identity theft and wire fraud conspiracy.
The indictment doesn’t specify the wireless companies targeted by the phishing and vishing schemes, but sources close to the investigation tell KrebsOnSecurity the two men were active members of OGusers, an online forum that caters to people selling access to hijacked social media accounts.
Bryan allegedly used the nickname “Champagne” on OGusers. On at least two occasions in the past few years, the OGusers forum was hacked and its user database — including private messages between forum members — were posted online. In a private message dated Nov. 15, 2019, Champagne can be seen asking another OGusers member to create a phishing site mimicking T-Mobile’s employee login page (t-mobileupdates[.]com).
Sources tell KrebsOnSecurity the two men are part of a larger conspiracy involving individuals from the United States and United Kingdom who’ve used vishing and phishing to trick work-at-home employees into giving away credentials needed to remotely access their employers’ networks.
The Federal Bureau of Investigation (FBI) and the Cybersecurity and Infrastructure Security Agency (CISA) on Thursday issued a joint alert to warn about the growing threat from voice phishing or “vishing” attacks targeting companies. The advisory came less than 24 hours after KrebsOnSecurity published an in-depth look at a crime group offering a service that people can hire to steal VPN credentials and other sensitive data from employees working remotely during the Coronavirus pandemic.
“The COVID-19 pandemic has resulted in a mass shift to working from home, resulting in increased use of corporate virtual private networks (VPNs) and elimination of in-person verification,” the alert reads. “In mid-July 2020, cybercriminals started a vishing campaign—gaining access to employee tools at multiple companies with indiscriminate targeting — with the end goal of monetizing the access.”
As noted in Wednesday’s story, the agencies said the phishing sites set up by the attackers tend to include hyphens, the target company’s name, and certain words — such as “support,” “ticket,” and “employee.” The perpetrators focus on social engineering new hires at the targeted company, and impersonate staff at the target company’s IT helpdesk.
The joint FBI/CISA alert (PDF) says the vishing gang also compiles dossiers on employees at the specific companies using mass scraping of public profiles on social media platforms, recruiter and marketing tools, publicly available background check services, and open-source research. From the alert:
“Actors first began using unattributed Voice over Internet Protocol (VoIP) numbers to call targeted employees on their personal cellphones, and later began incorporating spoofed numbers of other offices and employees in the victim company. The actors used social engineering techniques and, in some cases, posed as members of the victim company’s IT help desk, using their knowledge of the employee’s personally identifiable information—including name, position, duration at company, and home address—to gain the trust of the targeted employee.”
“The actors then convinced the targeted employee that a new VPN link would be sent and required their login, including any 2FA [2-factor authentication] or OTP [one-time passwords]. The actor logged the information provided by the employee and used it in real-time to gain access to corporate tools using the employee’s account.”
The alert notes that in some cases the unsuspecting employees approved the 2FA or OTP prompt, either accidentally or believing it was the result of the earlier access granted to the help desk impersonator. In other cases, the attackers were able to intercept the one-time codes by targeting the employee with SIM swapping, which involves social engineering people at mobile phone companies into giving them control of the target’s phone number.
The agencies said crooks use the vished VPN credentials to mine the victim company databases for their customers’ personal information to leverage in other attacks.
“The actors then used the employee access to conduct further research on victims, and/or to fraudulently obtain funds using varying methods dependent on the platform being accessed,” the alert reads. “The monetizing method varied depending on the company but was highly aggressive with a tight timeline between the initial breach and the disruptive cashout scheme.”
The advisory includes a number of suggestions that companies can implement to help mitigate the threat from these vishing attacks, including:
• Restrict VPN connections to managed devices only, using mechanisms like hardware checks or installed certificates, so user input alone is not enough to access the corporate VPN.
• Restrict VPN access hours, where applicable, to mitigate access outside of allowed times.
• Employ domain monitoring to track the creation of, or changes to, corporate, brand-name domains.
• Actively scan and monitor web applications for unauthorized access, modification, and anomalous activities.
• Employ the principle of least privilege and implement software restriction policies or other controls; monitor authorized user accesses and usage.
• Consider using a formalized authentication process for employee-to-employee communications made over the public telephone network where a second factor is used to
authenticate the phone call before sensitive information can be discussed.
• Improve 2FA and OTP messaging to reduce confusion about employee authentication attempts.
• Verify web links do not have misspellings or contain the wrong domain.
• Bookmark the correct corporate VPN URL and do not visit alternative URLs on the sole basis of an inbound phone call.
• Be suspicious of unsolicited phone calls, visits, or email messages from unknown individuals claiming to be from a legitimate organization. Do not provide personal information or information about your organization, including its structure or networks, unless you are certain of a person’s authority to have the information. If possible, try to verify the caller’s identity directly with the company.
• If you receive a vishing call, document the phone number of the caller as well as the domain that the actor tried to send you to and relay this information to law enforcement.
• Limit the amount of personal information you post on social networking sites. The internet is a public resource; only post information you are comfortable with anyone seeing.
• Evaluate your settings: sites may change their options periodically, so review your security and privacy settings regularly to make sure that your choices are still appropriate.
The COVID-19 epidemic has brought a wave of email phishing attacks that try to trick work-at-home employees into giving away credentials needed to remotely access their employers’ networks. But one increasingly brazen group of crooks is taking your standard phishing attack to the next level, marketing a voice phishing service that uses a combination of one-on-one phone calls and custom phishing sites to steal VPN credentials from employees.
According to interviews with several sources, this hybrid phishing gang has a remarkably high success rate, and operates primarily through paid requests or “bounties,” where customers seeking access to specific companies or accounts can hire them to target employees working remotely at home.
And over the past six months, the criminals responsible have created dozens if not hundreds of phishing pages targeting some of the world’s biggest corporations. For now at least, they appear to be focusing primarily on companies in the financial, telecommunications and social media industries.
“For a number of reasons, this kind of attack is really effective,” said Allison Nixon, chief research officer at New York-based cyber investigations firm Unit 221B. “Because of the Coronavirus, we have all these major corporations that previously had entire warehouses full of people who are now working remotely. As a result the attack surface has just exploded.”
TARGET: NEW HIRES
A typical engagement begins with a series of phone calls to employees working remotely at a targeted organization. The phishers will explain that they’re calling from the employer’s IT department to help troubleshoot issues with the company’s virtual private networking (VPN) technology.
The goal is to convince the target either to divulge their credentials over the phone or to input them manually at a website set up by the attackers that mimics the organization’s corporate email or VPN portal.
Zack Allen is director of threat intelligence for ZeroFOX, a Baltimore-based company that helps customers detect and respond to risks found on social media and other digital channels. Allen has been working with Nixon and several dozen other researchers from various security firms to monitor the activities of this prolific phishing gang in a bid to disrupt their operations.
Allen said the attackers tend to focus on phishing new hires at targeted companies, and will often pose as new employees themselves working in the company’s IT division. To make that claim more believable, the phishers will create LinkedIn profiles and seek to connect those profiles with other employees from that same organization to support the illusion that the phony profile actually belongs to someone inside the targeted firm.
“They’ll say ‘Hey, I’m new to the company, but you can check me out on LinkedIn’ or Microsoft Teams or Slack, or whatever platform the company uses for internal communications,” Allen said. “There tends to be a lot of pretext in these conversations around the communications and work-from-home applications that companies are using. But eventually, they tell the employee they have to fix their VPN and can they please log into this website.”
The domains used for these pages often invoke the company’s name, followed or preceded by hyphenated terms such as “vpn,” “ticket,” “employee,” or “portal.” The phishing sites also may include working links to the organization’s other internal online resources to make the scheme seem more believable if a target starts hovering over links on the page.
Allen said a typical voice phishing or “vishing” attack by this group involves at least two perpetrators: One who is social engineering the target over the phone, and another co-conspirator who takes any credentials entered at the phishing page and quickly uses them to log in to the target company’s VPN platform in real-time.
Time is of the essence in these attacks because many companies that rely on VPNs for remote employee access also require employees to supply some type of multi-factor authentication in addition to a username and password — such as a one-time numeric code generated by a mobile app or text message. And in many cases, those codes are only good for a short duration — often measured in seconds or minutes.
But these vishers can easily sidestep that layer of protection, because their phishing pages simply request the one-time code as well.
Allen said it matters little to the attackers if the first few social engineering attempts fail. Most targeted employees are working from home or can be reached on a mobile device. If at first the attackers don’t succeed, they simply try again with a different employee.
And with each passing attempt, the phishers can glean important details from employees about the target’s operations, such as company-specific lingo used to describe its various online assets, or its corporate hierarchy.
Thus, each unsuccessful attempt actually teaches the fraudsters how to refine their social engineering approach with the next mark within the targeted organization, Nixon said.
“These guys are calling companies over and over, trying to learn how the corporation works from the inside,” she said.
NOW YOU SEE IT, NOW YOU DON’T
All of the security researchers interviewed for this story said the phishing gang is pseudonymously registering their domains at just a handful of domain registrars that accept bitcoin, and that the crooks typically create just one domain per registrar account.
“They’ll do this because that way if one domain gets burned or taken down, they won’t lose the rest of their domains,” Allen said.
More importantly, the attackers are careful to do nothing with the phishing domain until they are ready to initiate a vishing call to a potential victim. And when the attack or call is complete, they disable the website tied to the domain.
This is key because many domain registrars will only respond to external requests to take down a phishing website if the site is live at the time of the abuse complaint. This requirement can stymie efforts by companies like ZeroFOX that focus on identifying newly-registered phishing domains before they can be used for fraud.
“They’ll only boot up the website and have it respond at the time of the attack,” Allen said. “And it’s super frustrating because if you file an abuse ticket with the registrar and say, ‘Please take this domain away because we’re 100 percent confident this site is going to be used for badness,’ they won’t do that if they don’t see an active attack going on. They’ll respond that according to their policies, the domain has to be a live phishing site for them to take it down. And these bad actors know that, and they’re exploiting that policy very effectively.”
SCHOOL OF HACKS
Both Nixon and Allen said the object of these phishing attacks seems to be to gain access to as many internal company tools as possible, and to use those tools to seize control over digital assets that can quickly be turned into cash. Primarily, that includes any social media and email accounts, as well as associated financial instruments such as bank accounts and any cryptocurrencies.
Nixon said she and others in her research group believe the people behind these sophisticated vishing campaigns hail from a community of young men who have spent years learning how to social engineer employees at mobile phone companies and social media firms into giving up access to internal company tools.
Traditionally, the goal of these attacks has been gaining control over highly-prized social media accounts, which can sometimes fetch thousands of dollars when resold in the cybercrime underground. But this activity gradually has evolved toward more direct and aggressive monetization of such access.
On July 15, a number of high-profile Twitter accounts were used to tweet out a bitcoin scam that earned more than $100,000 in a few hours. According to Twitter, that attack succeeded because the perpetrators were able to social engineer several Twitter employees over the phone into giving away access to internal Twitter tools.
Nixon said it’s not clear whether any of the people involved in the Twitter compromise are associated with this vishing gang, but she noted that the group showed no signs of slacking off after federal authorities charged several people with taking part in the Twitter hack.
“A lot of people just shut their brains off when they hear the latest big hack wasn’t done by hackers in North Korea or Russia but instead some teenagers in the United States,” Nixon said. “When people hear it’s just teenagers involved, they tend to discount it. But the kinds of people responsible for these voice phishing attacks have now been doing this for several years. And unfortunately, they’ve gotten pretty advanced, and their operational security is much better now.”
PROPER ADULT MONEY-LAUNDERING
While it may seem amateurish or myopic for attackers who gain access to a Fortune 100 company’s internal systems to focus mainly on stealing bitcoin and social media accounts, that access — once established — can be re-used and re-sold to others in a variety of ways.
“These guys do intrusion work for hire, and will accept money for any purpose,” Nixon said. “This stuff can very quickly branch out to other purposes for hacking.”
For example, Allen said he suspects that once inside of a target company’s VPN, the attackers may try to add a new mobile device or phone number to the phished employee’s account as a way to generate additional one-time codes for future access by the phishers themselves or anyone else willing to pay for that access.
Nixon and Allen said the activities of this vishing gang have drawn the attention of U.S. federal authorities, who are growing concerned over indications that those responsible are starting to expand their operations to include criminal organizations overseas…
“The person we spoke with at Citi’s fraud department kept insisting that yes, it was my wife that called because the call came from her mobile number,” Jim said. “The Citi employee was alarmed because she didn’t understand the whole notion of caller ID spoofing. And we both found it kind of disturbing that someone in fraud at such a major bank didn’t even understand that such a thing was possible.”
You may have heard that today’s phone fraudsters like to use caller ID spoofing services to make their scam calls seem more believable. But you probably didn’t know that these fraudsters also can use caller ID spoofing to trick your bank into giving up information about recent transactions on your account — data that can then be abused to make their phone scams more believable and expose you to additional forms of identity theft.
Last week, KrebsOnSecurity told the harrowing tale of a reader (a security expert, no less) who tried to turn the tables on his telephonic tormentors and failed spectacularly. In that episode, the people impersonating his bank not only spoofed the bank’s real phone number, but they were also pretending to be him on a separate call at the same time with his bank.
This foiled his efforts to make sure it was really his bank that called him, because he called his bank with another phone and the bank confirmed they currently were in a separate call with him discussing fraud on his account (however, the other call was the fraudster pretending to be him).
Shortly after that story ran, I heard from another reader — we’ll call him “Jim” since he didn’t want his real name used for this story — whose wife was the target of a similar scam, albeit with an important twist: The scammers were armed with information about a number of her recent financial transactions, which he claims they got from the bank’s own automated phone system just by spoofing her phone number.
“When they originally called my wife, there were no fraudulent transactions on her account, but they were able to specify the last three transactions she had made, which combined with the caller-ID had mistakenly earned her trust,” Jim explained. “After we figured out what was going on, we were left asking ourselves how the crooks had obtained her last three transactions without breaking into her account online. As it turned out, calling the phone number on the back of the credit card from the phone number linked with the card provided the most recent transactions without providing any form of authentication.”
Jim said he was so aghast at this realization that he called the same number from his phone and tried accessing his account, which is also at Citi but wholly separate from his spouse’s. Sure enough, he said, as long as he was calling from the number on file for his account, the automated system let him review recent transactions without any further authentication.
So, it seemed the crooks would spoof caller ID when calling Citibank, as well as when calling the target/victim.
“I confirmed on my separate Citi card that they often (but not quite always) were providing the transaction details,” Jim said. “I was appalled that Citi would do that. So, it seemed the crooks would spoof caller ID when calling Citibank, as well as when calling the target/victim.”
The incident Jim described happened in late January 2020, and Citi may have changed its procedures since then. But in a phone interview with KrebsOnSecurity earlier this week, Jim made a call to Citi’s automated system from his mobile phone on file with the bank, and I could hear Citi’s systems asking him to enter the last four digits of his credit card number before he could review recent transactions.
The request for the last four of the customer’s credit card number was consistent with my own testing, which relied on a caller ID spoofing service advertised in the cybercrime underground and aimed at a Citi account controlled by this author.
In one test, the spoofed call let KrebsOnSecurity hear recent transaction data — where and when the transaction was made, and how much was spent — after providing the automated system the last four digits of the account’s credit card number. In another test, the automated system asked for the account holder’s full Social Security number.
October 18, 2018
Most of us have been trained to be wary of clicking on links and attachments that arrive in emails unexpected, but it’s easy to forget scam artists are constantly dreaming up innovations that put a new shine on old-fashioned telephone-based phishing scams. Think you’re too smart to fall for one? Think again: Even technology experts are getting taken in by some of the more recent schemes (or very nearly)…