The Fake Browser Update Scam Gets a Makeover

One of the oldest malware tricks in the book — hacked websites claiming visitors need to update their Web browser before they can view any content — has roared back to life in the past few months. New research shows the attackers behind one such scheme have developed an ingenious way of keeping their malware from being taken down by security experts or law enforcement: By hosting the malicious files on a decentralized, anonymous cryptocurrency blockchain.

In August 2023, security researcher Randy McEoin blogged about a scam he dubbed ClearFake, which uses hacked WordPress sites to serve visitors with a page that claims you need to update your browser before you can view the content.

The fake browser alerts are specific to the browser you’re using, so if you’re surfing the Web with Chrome, for example, you’ll get a Chrome update prompt. Those who are fooled into clicking the update button will have a malicious file dropped on their system that tries to install an information stealing trojan.

Earlier this month, researchers at the Tel Aviv-based security firm Guardio said they tracked an updated version of the ClearFake scam that included an important evolution. Previously, the group had stored its malicious update files on Cloudflare, Guardio said.

But when Cloudflare blocked those accounts the attackers began storing their malicious files as cryptocurrency transactions in the Binance Smart Chain (BSC), a technology designed to run decentralized apps and “smart contracts,” or coded agreements that execute actions automatically when certain conditions are met.

Nati Tal, head of security at Guardio Labs, the research unit at Guardio, said the malicious scripts stitched into hacked WordPress sites will create a new smart contract on the BSC Blockchain, starting with a unique, attacker-controlled blockchain address and a set of instructions that defines the contract’s functions and structure. When that contract is queried by a compromised website, it will return an obfuscated and malicious payload.

“These contracts offer innovative ways to build applications and processes,” Tal wrote along with his Guardio colleague Oleg Zaytsev. “Due to the publicly accessible and unchangeable nature of the blockchain, code can be hosted ‘on-chain’ without the ability for a takedown.”

Tal said hosting malicious files on the Binance Smart Chain is ideal for attackers because retrieving the malicious contract is a cost-free operation that was originally designed for the purpose of debugging contract execution issues without any real-world impact.

“So you get a free, untracked, and robust way to get your data (the malicious payload) without leaving traces,” Tal said.

In response to questions from KrebsOnSecurity, the BNB Smart Chain (BSC) said its team is aware of the malware abusing its blockchain, and is actively addressing the issue. The company said all addresses associated with the spread of the malware have been blacklisted, and that its technicians had developed a model to detect future smart contracts that use similar methods to host malicious scripts.

“This model is designed to proactively identify and mitigate potential threats before they can cause harm,” BNB Smart Chain wrote. “The team is committed to ongoing monitoring of addresses that are involved in spreading malware scripts on the BSC. To enhance their efforts, the tech team is working on linking identified addresses that spread malicious scripts to centralized KYC [Know Your Customer] information, when possible.”

Guardio says the crooks behind the BSC malware scheme are using the same malicious code as the attackers that McEoin wrote about in August, and are likely the same group. But a report published today by email security firm Proofpoint says the company is currently tracking at least four distinct threat actor groups that use fake browser updates to distribute malware.

Proofpoint notes that the core group behind the fake browser update scheme has been using this technique to spread malware for the past five years, primarily because the approach still works well.

“Fake browser update lures are effective because threat actors are using an end-user’s security training against them,” Proofpoint’s Dusty Miller wrote. “In security awareness training, users are told to only accept updates or click on links from known and trusted sites, or individuals, and to verify sites are legitimate. The fake browser updates abuse this training because they compromise trusted sites and use JavaScript requests to quietly make checks in the background and overwrite the existing website with a browser update lure. To an end user, it still appears to be the same website they were intending to visit and is now asking them to update their browser.”

More than a decade ago, this site published Krebs’s Three Rules for Online Safety, of which Rule #1 was, “If you didn’t go looking for it, don’t install it.” It’s nice to know that this technology-agnostic approach to online safety remains just as relevant today.

Binance's Smart Chain Exploited in New 'EtherHiding' Malware Campaign

Threat actors have been observed serving malicious code by utilizing Binance's Smart Chain (BSC) contracts in what has been described as the "next level of bulletproof hosting." The campaign, detected two months ago, has been codenamed EtherHiding by Guardio Labs. The novel twist marks the latest iteration in an ongoing malware campaign that leverages compromised WordPress sites to serve

Battle with Bots Prompts Mass Purge of Amazon, Apple Employee Accounts on LinkedIn

On October 10, 2022, there were 576,562 LinkedIn accounts that listed their current employer as Apple Inc. The next day, half of those profiles no longer existed. A similarly dramatic drop in the number of LinkedIn profiles claiming employment at Amazon comes as LinkedIn is struggling to combat a significant uptick in the creation of fake employee accounts that pair AI-generated profile photos with text lifted from legitimate users.

Jay Pinho is a developer who is working on a product that tracks company data, including hiring. Pinho has been using LinkedIn to monitor daily employee headcounts at several dozen large organizations, and last week he noticed that two of them had far fewer people claiming to work for them than they did just 24 hours previously.

Pinho’s screenshot below shows the daily count of employees as displayed on Amazon’s LinkedIn homepage. Pinho said his scraper shows that the number of LinkedIn profiles claiming current roles at Amazon fell from roughly 1.25 million to 838,601 in just one day, a 33 percent drop:

As stated above, the number of LinkedIn profiles that claimed to work at Apple fell by approximately 50 percent on Oct. 10, according to Pinho’s analysis:

Neither Amazon or Apple responded to requests for comment. LinkedIn declined to answer questions about the account purges, saying only that the company is constantly working to keep the platform free of fake accounts. In June, LinkedIn acknowledged it was seeing a rise in fraudulent activity happening on the platform.

KrebsOnSecurity hired Menlo Park, Calif.-based SignalHire to check Pinho’s numbers. SignalHire keeps track of active and former profiles on LinkedIn, and during the Oct 9-11 timeframe SignalHire said it saw somewhat smaller but still unprecedented drops in active profiles tied to Amazon and Apple.

“The drop in the percentage of 7-10 percent [of all profiles], as it happened [during] this time, is not something that happened before,” SignalHire’s Anastacia Brown told KrebsOnSecurity.

Brown said the normal daily variation in profile numbers for these companies is plus or minus one percent.

“That’s definitely the first huge drop that happened throughout the time we’ve collected the profiles,” she said.

In late September 2022, KrebsOnSecurity warned about the proliferation of fake LinkedIn profiles for Chief Information Security Officer (CISO) roles at some of the world’s largest corporations. A follow-up story on Oct. 5 showed how the phony profile problem has affected virtually all executive roles at corporations, and how these fake profiles are creating an identity crisis for the businesses networking site and the companies that rely on it to hire and screen prospective employees.

A day after that second story ran, KrebsOnSecurity heard from a recruiter who noticed the number of LinkedIn profiles that claimed virtually any role in network security had dropped seven percent overnight. LinkedIn declined to comment about that earlier account purge, saying only that, “We’re constantly working at taking down fake accounts.”

It’s unclear whether LinkedIn is responsible for this latest account purge, or if individually affected companies are starting to take action on their own. The timing, however, argues for the former, as the account purges for Apple and Amazon employees tracked by Pinho appeared to happen within the same 24 hour period.

It’s also unclear who or what is behind the recent proliferation of fake executive profiles on LinkedIn. Cybersecurity firm Mandiant (recently acquired by Google) told Bloomberg that hackers working for the North Korean government have been copying resumes and profiles from leading job listing platforms LinkedIn and Indeed, as part of an elaborate scheme to land jobs at cryptocurrency firms.

On this point, Pinho said he noticed an account purge in early September that targeted fake profiles tied to jobs at cryptocurrency exchange Binance. Up until Sept. 3, there were 7,846 profiles claiming current executive roles at Binance. The next day, that number stood at 6,102, a 23 percent drop (by some accounts that 6,102 head count is still wildly inflated).

Fake profiles also may be tied to so-called “pig butchering” scams, wherein people are lured by flirtatious strangers online into investing in cryptocurrency trading platforms that eventually seize any funds when victims try to cash out.

In addition, identity thieves have been known to masquerade on LinkedIn as job recruiters, collecting personal and financial information from people who fall for employment scams.

Nicholas Weaver, a researcher for the International Computer Science Institute at University of California, Berkeley, suggested another explanation for the recent glut of phony LinkedIn profiles: Someone may be setting up a mass network of accounts in order to more fully scrape profile information from the entire platform.

“Even with just a standard LinkedIn account, there’s a pretty good amount of profile information just in the default two-hop networks,” Weaver said. “We don’t know the purpose of these bots, but we know creating bots isn’t free and creating hundreds of thousands of bots would require a lot of resources.”

In response to last week’s story about the explosion of phony accounts on LinkedIn, the company said it was exploring new ways to protect members, such as expanding email domain verification. Under such a scheme, LinkedIn users would be able to publicly attest that their profile is accurate by verifying that they can respond to email at the domain associated with their current employer.

LinkedIn claims that its security systems detect and block approximately 96 percent of fake accounts. And despite the recent purges, LinkedIn may be telling the truth, Weaver said.

“There’s no way you can test for that,” he said. “Because technically, it may be that there were actually 100 million bots trying to sign up at LinkedIn as employees at Amazon.”

Weaver said the apparent mass account purge at LinkedIn underscores the size of the bot problem, and could present a “real and material change” for LinkedIn.

“It may mean the statistics they’ve been reporting about usage and active accounts are off by quite a bit,” Weaver said.

Hackers Steal $100 Million Cryptocurrency from Binance Bridge

BNB Chain, a blockchain linked to the Binance cryptocurrency exchange, disclosed an exploit on a cross-chain bridge that drained around $100 million in digital assets. "There was an exploit affecting the native cross-chain bridge between BNB Beacon Chain (BEP2) and BNB Smart Chain (BEP20 or BSC), known as 'BSC Token Hub,'" it said last week. "The exploit was through a sophisticated forging of