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It’s not often that a zero-day vulnerability causes a network security vendor to urge customers to physically remove and decommission an entire line of affected hardware — as opposed to just applying software updates. But experts say that is exactly what transpired this week with Barracuda Networks, as the company struggled to combat a sprawling malware threat which appears to have undermined its email security appliances in such a fundamental way that they can no longer be safely updated with software fixes.
The Barracuda Email Security Gateway (ESG) 900 appliance.
Campbell, Calif. based Barracuda said it hired incident response firm Mandiant on May 18 after receiving reports about unusual traffic originating from its Email Security Gateway (ESG) devices, which are designed to sit at the edge of an organization’s network and scan all incoming and outgoing email for malware.
On May 19, Barracuda identified that the malicious traffic was taking advantage of a previously unknown vulnerability in its ESG appliances, and on May 20 the company pushed a patch for the flaw to all affected appliances (CVE-2023-2868).
In its security advisory, Barracuda said the vulnerability existed in the Barracuda software component responsible for screening attachments for malware. More alarmingly, the company said it appears attackers first started exploiting the flaw in October 2022.
But on June 6, Barracuda suddenly began urging its ESG customers to wholesale rip out and replace — not patch — affected appliances.
“Impacted ESG appliances must be immediately replaced regardless of patch version level,” the company’s advisory warned. “Barracuda’s recommendation at this time is full replacement of the impacted ESG.”
In a statement, Barracuda said it will be providing the replacement product to impacted customers at no cost, and that not all ESG appliances were compromised.
“No other Barracuda product, including our SaaS email solutions, were impacted by this vulnerability,” the company said. “If an ESG appliance is displaying a notification in the User Interface, the ESG appliance had indicators of compromise. If no notification is displayed, we have no reason to believe that the appliance has been compromised at this time.”
Nevertheless, the statement says that “out of an abundance of caution and in furtherance of our containment strategy, we recommend impacted customers replace their compromised appliance.”
“As of June 8, 2023, approximately 5% of active ESG appliances worldwide have shown any evidence of known indicators of compromise due to the vulnerability,” the statement continues. “Despite deployment of additional patches based on known IOCs, we continue to see evidence of ongoing malware activity on a subset of the compromised appliances. Therefore, we would like customers to replace any compromised appliance with a new unaffected device.”
Rapid7‘s Caitlin Condon called this remarkable turn of events “fairly stunning,” and said there appear to be roughly 11,000 vulnerable ESG devices still connected to the Internet worldwide.
“The pivot from patch to total replacement of affected devices is fairly stunning and implies the malware the threat actors deployed somehow achieves persistence at a low enough level that even wiping the device wouldn’t eradicate attacker access,” Condon wrote.
Barracuda said the malware was identified on a subset of appliances that allowed the attackers persistent backdoor access to the devices, and that evidence of data exfiltration was identified on some systems.
Rapid7 said it has seen no evidence that attackers are using the flaw to move laterally within victim networks. But that may be small consolation for Barracuda customers now coming to terms with the notion that foreign cyberspies probably have been hoovering up all their email for months.
Nicholas Weaver, a researcher at University of California, Berkeley’s International Computer Science Institute (ICSI), said it is likely that the malware was able to corrupt the underlying firmware that powers the ESG devices in some irreparable way.
“One of the goals of malware is to be hard to remove, and this suggests the malware compromised the firmware itself to make it really hard to remove and really stealthy,” Weaver said. “That’s not a ransomware actor, that’s a state actor. Why? Because a ransomware actor doesn’t care about that level of access. They don’t need it. If they’re going for data extortion, it’s more like a smash-and-grab. If they’re going for data ransoming, they’re encrypting the data itself — not the machines.”
In addition to replacing devices, Barracuda says ESG customers should also rotate any credentials connected to the appliance(s), and check for signs of compromise dating back to at least October 2022 using the network and endpoint indicators the company has released publicly.
Update, June 9, 11:55 a.m. ET: Barracuda has issued an updated statement about the incident, portions of which are now excerpted above.
One way to tame your email inbox is to get in the habit of using unique email aliases when signing up for new accounts online. Adding a “+” character after the username portion of your email address — followed by a notation specific to the site you’re signing up at — lets you create an infinite number of unique email addresses tied to the same account. Aliases can help users detect breaches and fight spam. But not all websites allow aliases, and they can complicate account recovery. Here’s a look at the pros and cons of adopting a unique alias for each website.
What is an email alias? When you sign up at a site that requires an email address, think of a word or phrase that represents that site for you, and then add that prefaced by a “+” sign just to the left of the “@” sign in your email address. For instance, if I were signing up at example.com, I might give my email address as krebsonsecurity+example@gmail.com. Then, I simply go back to my inbox and create a corresponding folder called “Example,” along with a new filter that sends any email addressed to that alias to the Example folder.
Importantly, you don’t ever use this alias anywhere else. That way, if anyone other than example.com starts sending email to it, it is reasonable to assume that example.com either shared your address with others or that it got hacked and relieved of that information. Indeed, security-minded readers have often alerted KrebsOnSecurity about spam to specific aliases that suggested a breach at some website, and usually they were right, even if the company that got hacked didn’t realize it at the time.
Alex Holden, founder of the Milwaukee-based cybersecurity consultancy Hold Security, said many threat actors will scrub their distribution lists of any aliases because there is a perception that these users are more security- and privacy-focused than normal users, and are thus more likely to report spam to their aliased addresses.
Holden said freshly-hacked databases also are often scrubbed of aliases before being sold in the underground, meaning the hackers will simply remove the aliased portion of the email address.
“I can tell you that certain threat groups have rules on ‘+*@’ email address deletion,” Holden said. “We just got the largest credentials cache ever — 1 billion new credentials to us — and most of that data is altered, with aliases removed. Modifying credential data for some threat groups is normal. They spend time trying to understand the database structure and removing any red flags.”
According to the breach tracking site HaveIBeenPwned.com, only about .03 percent of the breached records in circulation today include an alias.
Email aliases are rare enough that seeing just a few email addresses with the same alias in a breached database can make it trivial to identify which company likely got hacked and leaked said database. That’s because the most common aliases are simply the name of the website where the signup takes place, or some abbreviation or shorthand for it.
Hence, for a given database, if there are more than a handful of email addresses that have the same alias, the chances are good that whatever company or website corresponds to that alias has been hacked.
That might explain the actions of Allekabels, a large Dutch electronics web shop that suffered a data breach in 2021. Allekabels said a former employee had stolen data on 5,000 customers, and that those customers were then informed about the data breach by Allekabels.
But Dutch publication RTL Nieuws said it obtained a copy of the Allekabels user database from a hacker who was selling information on 3.6 million customers at the time, and found that the 5,000 number cited by the retailer corresponded to the number of customers who’d signed up using an alias. In essence, RTL argued, the company had notified only those most likely to notice and complain that their aliased addresses were suddenly receiving spam.
“RTL Nieuws has called more than thirty people from the database to check the leaked data,” the publication explained. “The customers with such a unique email address have all received a message from Allekabels that their data has been leaked – according to Allekabels they all happened to be among the 5000 data that this ex-employee had stolen.”
HaveIBeenPwned’s Hunt arrived at the conclusion that aliases account for about .03 percent of registered email addresses by studying the data leaked in the 2013 breach at Adobe, which affected at least 38 million users. Allekabels’s ratio of aliased users was considerably higher than Adobe’s — .14 percent — but then again European Internet users tend to be more privacy-conscious.
While overall adoption of email aliases is still quite low, that may be changing. Apple customers who use iCloud to sign up for new accounts online automatically are prompted to use Apple’s Hide My Email feature, which creates the account using a unique email address that automatically forwards to a personal inbox.
What are the downsides to using email aliases, apart from the hassle of setting them up? The biggest downer is that many sites won’t let you use a “+” sign in your email address, even though this functionality is clearly spelled out in the email standard.
Also, if you use aliases, it helps to have a reliable mnemonic to remember the alias used for each account (this is a non-issue if you create a new folder or rule for each alias). That’s because knowing the email address for an account is generally a prerequisite for resetting the account’s password, and if you can’t remember the alias you added way back when you signed up, you may have limited options for recovering access to that account if you at some point forget your password.
What about you, Dear Reader? Do you rely on email aliases? If so, have they been useful? Did I neglect to mention any pros or cons? Feel free to sound off in the comments below.
Email scammers sent an Uber to the home of an 80-year-old woman who responded to a well-timed email scam, in a bid to make sure she went to the bank and wired money to the fraudsters. In this case, the woman figured out she was being scammed before embarking for the bank, but her story is a chilling reminder of how far crooks will go these days to rip people off.
Travis Hardaway is a former music teacher turned app developer from Towson, Md. Hardaway said his mother last month replied to an email she received regarding an appliance installation from BestBuy/GeekSquad. Hardaway said the timing of the scam email couldn’t have been worse: His mom’s dishwasher had just died, and she’d paid to have a new one delivered and installed.
“I think that’s where she got confused, because she thought the email was about her dishwasher installation,” Hardaway told KrebsOnSecurity.
Hardaway said his mom initiated a call to the phone number listed in the phony BestBuy email, and that the scammers told her she owed $160 for the installation, which seemed right at the time. Then the scammers asked her to install remote administration software on her computer so that they could control the machine from afar and assist her in making the payment.
After she logged into her bank and savings accounts with scammers watching her screen, the fraudster on the phone claimed that instead of pulling $160 out of her account, they accidentally transferred $160,000 to her account. They said they they needed her help to make sure the money was “returned.”
“They took control of her screen and said they had accidentally transferred $160,000 into her account,” Hardaway said. “The person on the phone told her he was going to lose his job over this transfer error, that he didn’t know what to do. So they sent her some information about where to wire the money, and asked her to go to the bank. But she told them, ‘I don’t drive,’ and they told her, “No problem, we’re sending an Uber to come help you to the bank.'”
Hardaway said he was out of town when all this happened, and that thankfully his mom eventually grew exasperated and gave up trying to help the scammers.
“They told her they were sending an Uber to pick her up and that it was on its way,” Hardaway said. “I don’t know if the Uber ever got there. But my mom went over to the neighbor’s house and they saw it for what it was — a scam.”
Hardaway said he has since wiped her computer, reinstalled the operating system and changed her passwords. But he says the incident has left his mom rattled.
“She’s really second-guessing herself now,” Hardaway said. “She’s not computer-savvy, and just moved down here from Boston during COVID to be near us, but she’s living by herself and feeling isolated and vulnerable, and stuff like this doesn’t help.”
According to the Federal Bureau of Investigation (FBI), seniors are often targeted because they tend to be trusting and polite. More importantly, they also usually have financial savings, own a home, and have good credit—all of which make them attractive to scammers.
“Additionally, seniors may be less inclined to report fraud because they don’t know how, or they may be too ashamed of having been scammed,” the FBI warned in May. “They might also be concerned that their relatives will lose confidence in their abilities to manage their own financial affairs. And when an elderly victim does report a crime, they may be unable to supply detailed information to investigators.”
In 2021, more than 92,000 victims over the age of 60 reported losses of $1.7 billion to the FBI’s Internet Crime Complaint Center (IC3). The FBI says that represents a 74 percent increase in losses over losses reported in 2020.
The abuse of ride-sharing services to scam the elderly is not exactly new. Authorities in Tampa, Fla. say they’re investigating an incident from December 2021 where fraudsters who’d stolen $700,000 from elderly grandparents used Uber rides to pick up bundles of cash from their victims.
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