It was just a little over a year ago that the Rhadamanthys stealer was first publicly seen distributed via malicious ads. Throughout 2023, we observed a continuation in malvertising chains related to software downloads.

Fast forward to 2024 and the same malvertising campaigns are still going on. After a lull last summer, we noticed an increase since the fall which so far has been sustained. The most recent targeted searches are for Parsec and FreeCad, followed by WinSCP, Advanced IP Scanner, Slack and Notion.

Threat actors are targeting business users with payloads such as FakeBat, Nitrogen or Hijackloader. One other malware family we have seen here and there is Rhadamanthys. In this blog post, we detail the latest distribution chain related to this malware.

Key points

• Rhadamanthys is an infostealer distributed via malspam and malvertising.
• Google searches for popular software such as Notion return malicious ads.
• Threat actors are using decoy websites to trick users into downloading malware.
• The initial payload is a dropper that retrieves Rhadamanthys via a URL pasted online.
• The TexBin paste site shows the URL was seen/accessed 8.5K times.

Malicious ad

Threat actors continue to impersonate well-known brands via sponsored search results. As can be seen below in a search for Notion (productivity software), an extremely deceiving ad is shown. Because it includes the official logo and website for Notion, most users will not think twice and click on the link.

While the ad looks real on the surface, the Google Ads Transparency Center page (which can be accessed by clicking on the menu right next to the ad’s URL) shows this ad was created by a certain ‘BUDNIK PAWEŁ’ from Poland. According to the same report, the first ad first appeared on January 23, 2024.

As a matter of fact, we have been tracking this fraudulent advertiser for a few weeks and had reported it to Google in early February, when we first ran into it. At the time, victims who clicked the ad and visited the site were tricked with a download for NetSupport RAT.

In this more recent campaign, the threat actor is pushing Rhadamanthys as the final payload, after an initial dropper. In the web traffic seen below, we can see that the threat actor uses a number of redirects to evade detection. URL shorteners and redirectors are quite common for the initial ad click, often followed by an attacker-controlled domain responsible for cloaking traffic.

There is one more check within the browser via JavaScript to detect virtual machines before the actual landing page is displayed to the victim.

Landing page and payload

The landing page is the decoy site that victims will see after they click on the ad. Apart from the URL in the address bar, it looks very similar to the official web site for Notion, although somewhat simplified. There are two download buttons, one for Mac and the other for Windows.

The Mac payload (Notion.dmg) is a new variant of Atomic Stealer. Thanks to Luis Castellanos from Block for sharing a sample with us.

The Windows binary is a signed file but its digital signature is not valid. The name of the signer that shows here is from the inventor of PuTTY, a popular admin tool. This digital certificate is likely fake or was revoked, but it may evade detection in some cases.

This dropper contacts the paste site TextBin where it retrieves a URL for the followup payload, Rhadamanthys. If the numbers are correct this unlisted paste was viewed 8.5k times already.

Rhadamanthys attempts to steal credentials stored in applications such as PuTTY, WinSCP and mail programs (screenshot from Joe Sandbox):

Upon execution, Rhadamanthys reports to its command and control server, sends and receives data.

Conclusion

Not a lot has changed with malvertising campaigns focused on software downloads as we enter the second year of actively tracking them. Sponsored search results continue to be highly misleading due to the fact that any verified individual is able to impersonate popular brands by using their logo and official site within the ad itself.

We are aware of reports shared within private circles, that businesses were compromised after an employee clicked on a malicious ad. Follow-up activities post infection include the usual ‘pentesting tools’ that precede a company-wide breach or ransomware deployment.

The infrastructure used in this particular attack was reported to the relevant parties. Malwarebytes and ThreatDown customers are protected against the payloads and distribution sites.

Additionally, EDR customers who have DNS Filtering can proactively block online ads by enabling the rule for advertisements. This is a simple, and yet powerful way to prevent malvertising across an entire organization or in specific areas.

Endpoint users will see a customizable message when they click on an ad such as those that appear on a search engine results page:

Indicators of Compromise

Malvertising chain

pantovawy.page[.]link
cerisico[.]net
notione.my-apk[.]com
alternativebehavioralconcepts[.]org

Dropper

6f4a0cc0fa22b66f75f5798d3b259d470beb776d79de2264c2affc0b5fa924a2

Dropper IP

185[.]172[.]128[.]169

Rhadamanthys download URL

yogapets[.]xyz/@abcmse1.exe
birdarid[.]org/@abcnp.exe

Rhadamanthys

e179a9e5d75d56140d11cbd29d92d8137b0a73f964dd3cfd46564ada572a3109
679fad2fd86d2fd9e1ec38fa15280c1186f35343583c7e83ab382b8c255f9e18

Rhadamanthys C2

185[.]172[.]128[.]170

On the internet, people need to worry about more than just opening suspicious email attachments or entering their sensitive information into harmful websites—they also need to worry about their Google searches.

That’s because last year, as revealed in our 2024 ThreatDown State of Malware report, cybercriminals flocked to a malware delivery method that doesn’t require they know a victim’s email address, login credentials, personal information, or, anything, really.

Instead, cybercriminals just need to fool someone into clicking on a search result that looks remarkably legitimate.

This is the work of “malicious advertising,” or “malvertising,” for short. Malvertising is not malware itself. Instead, it’s a sneaky process of placing malware, viruses, or other cyber infections on a person’s computer, tablet, or smart phone. The malware that eventually slips onto a person’s device comes in many varieties, but cybercriminals tend to favor malware that can steal a person’s login credentials and information. With this newly stolen information, cybercriminals can then pry into sensitive online accounts that belong to the victim.

But before any of that digital theft can occur, cybercriminals must first ensnare a victim, and they do this by abusing the digital ad infrastructure underpinning Google search results.

Think about searching on Google for “running shoes”—you’ll likely see ads for Nike and Adidas. A Google search for “best carry-on luggage” will invariably produce ads for the consumer brands Monos and Away. And a Google search for a brand like Amazon will show, as expected, ads for Amazon.

But cybercriminals know this, and in response, they’ve created ads that look legitimate, but instead direct victims to malicious websites that carry malware. The websites themselves, too, bear a striking resemblance to whatever product or brand they’re imitating, so as to maintain a charade of legitimacy. From these websites, users download what they think is a valid piece of software, instead downloading malware that leaves them open to further attacks.

It’s true that malvertising is often understood as a risk to businesses, but the copycat websites that are created by cybercriminals can and often do impersonate popular brands for everyday users, too.

As revealed in our 2024 ThreatDown State of Malware report, the five most impersonated brands for malvertising last year included:

1. Amazon
2. Rufus
3. Weebly
4. NotePad++
5. TradingView

These five brands may not all carry the same familiarity, but their products and services capture a broad swath of user interest, from Weebly’s website creation products, to TradingView’s investment trading platform, to Rufus’s niche-but-useful portable OS booting tool.

Why the increase in malvertising last year?

If Google ads have been around for more than a decade, why are they only being abused by cybercriminals now? The truth is, malvertising has been around for years, but a particular resurgence was recorded more recently.

In 2022, cybercriminals lost access to one of their favorite methods of delivering malware.

That summer, Microsoft announced that it would finally block “macros” that were embedded into files that were downloaded from the internet. Macros are essentially instructions that users can program so that multiple tasks can be bundled together. The danger, though, is that cybercriminals would pre-program macros within certain files for Microsoft Word, Excel, or PowerPoint, and then send those files as malicious email attachments. Once those attachments were downloaded and opened by users, the embedded macros would trigger a set of instructions directing a person’s computer to install malware from a dangerous website online.

Macros were a scourge for cybersecurity for years, as they were effective and easy to deliver.

But when Microsoft restricted macro capabilities in 2022, cybercriminals needed to find another malware delivery channel. They focused on malvertising.

Today’s malvertising is increasingly sophisticated, as cybercriminals can create and purchase online ads that target specific types of users based on location and demographics. Concerningly, modern malvertising can even avoid basic fraud detection as cybercriminals can create websites that determine whether a user is a real person or simply a bot that is trawling the web to find and flag malicious activity.

How to protect against malvertising

The threat of malvertising is multi-layered: There are the fraudulent ads that cybercriminals place on Google search results, the malicious websites that imitate legitimate brands and companies to convince users to download malware, and the malware infection itself.

As such, any successful defense strategy must be multi-layered.

For safe browsing, people can rely on Malwarebytes Browser Guard, a browser extension that blocks third-party tracking and flags malicious websites known to be in the control of cybercriminals. As we wrote before:

“Malwarebytes Browser Guard provides additional protection to standard ad-blocking features by covering a larger area of the attack chain all the way to domains controlled by attackers. Thanks to its built-in heuristic engine it can also proactively block never-before-seen malicious websites.”

The problem with malvertising, though, is that new malicious websites are created every single day. Cybersecurity defenders, then, are often caught in a game of catch-up.

Here, users can find safety from Malwarebytes Premium, which provides real-time protection to detect and stop any cyberthreats that get installed onto a device, even if those threats are masquerading as legitimate apps or software.

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We don’t just report on threats—we remove them

Cybersecurity risks should never spread beyond a headline. Keep threats off your devices by downloading Malwarebytes today.

Today on the Lock and Code podcast…

If your IT and security teams think malware is bad, wait until they learn about everything else.

In 2024, the modern cyberattack is a segmented, prolonged, and professional effort, in which specialists create strictly financial alliances to plant malware on unsuspecting employees, steal corporate credentials, slip into business networks, and, for a period of days if not weeks, simply sit and watch and test and prod, escalating their privileges while refraining from installing any noisy hacking tools that could be flagged by detection-based antivirus scans.

In fact, some attacks have gone so “quiet” that they involve no malware at all. Last year, some ransomware gangs refrained from deploying ransomware in their own attacks, opting to steal sensitive data and then threaten to publish it online if their victims refused to pay up—a method of extracting a ransom that is entirely without ransomware.

Understandably, security teams are outflanked. Defending against sophisticated, multifaceted attacks takes resources, technologies, and human expertise. But not every organization has that at hand.

What, then, are IT-constrained businesses to do?

Today, on the Lock and Code podcast with host David Ruiz, we speak with Jason Haddix, the former Chief Information Security Officer at the videogame developer Ubisoft, about how he and his colleagues from other companies faced off against modern adversaries who, during a prolonged crime spree, plundered employee credentials from the dark web, subverted corporate 2FA protections, and leaned heavily on internal web access to steal sensitive documentation.

Haddix, who launched his own cybersecurity training and consulting firm Arcanum Information Security this year, said he learned so much during his time at Ubisoft that he and his peers in the industry coined a new, humorous term for attacks that abuse internet-connected platforms: “A browser and a dream.”

“When you first hear that, you’re like, ‘Okay, what could a browser give you inside of an organization?'”

But Haddix made it clear:

“On the internal LAN, you have knowledge bases like SharePoint, Confluence, MediaWiki. You have dev and project management sites like Trello, local Jira, local Redmine. You have source code managers, which are managed via websites—Git, GitHub, GitLab, Bitbucket, Subversion. You have repo management, build servers, dev platforms, configuration, management platforms, operations, front ends. These are all websites.”

Tune in today.

Show notes and credits:

Intro Music: “Spellbound” by Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/
Outro Music: “Good God” by Wowa (unminus.com)
LLM Prompt Injection Game: https://gandalf.lakera.ai/

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Overwhelmed by modern cyberthreats? ThreatDown can help.

The 2024 ThreatDown State of Malware report is a comprehensive analysis of six pressing cyberthreats this year—including Big Game ransomware, Living Off The Land (LOTL) attacks, and malvertising—with strategies on how IT and security teams can protect against them.

Google continues to struggle with cybercriminals running malicious ads on its search platform to trick people into downloading booby-trapped copies of popular free software applications. The malicious ads, which appear above organic search results and often precede links to legitimate sources of the same software, can make searching for software on Google a dicey affair.

Google says keeping users safe is a top priority, and that the company has a team of thousands working around the clock to create and enforce their abuse policies. And by most accounts, the threat from bad ads leading to backdoored software has subsided significantly compared to a year ago.

But cybercrooks are constantly figuring out ingenious ways to fly beneath Google’s anti-abuse radar, and new examples of bad ads leading to malware are still too common.

For example, a Google search earlier this week for the free graphic design program FreeCAD produced the following result, which shows that a “Sponsored” ad at the top of the search results is advertising the software available from freecad-us[.]org. Although this website claims to be the official FreeCAD website, that honor belongs to the result directly below — the legitimate freecad.org.

How do we know freecad-us[.]org is malicious? A review at DomainTools.com show this domain is the newest (registered Jan. 19, 2024) of more than 200 domains at the Internet address 93.190.143[.]252 that are confusingly similar to popular software titles, including dashlane-project[.]com, filezillasoft[.]com, keepermanager[.]com, and libreofficeproject[.]com.

Some of the domains at this Netherlands host appear to be little more than software review websites that steal content from established information sources in the IT world, including Gartner, PCWorld, Slashdot and TechRadar.

Other domains at 93.190.143[.]252 do serve actual software downloads, but none of them are likely to be malicious if one visits the sites through direct navigation. If one visits openai-project[.]org and downloads a copy of the popular Windows desktop management application Rainmeter, for example, the file that is downloaded has the same exact file signature as the real Rainmeter installer available from rainmeter.net.

But this is only a ruse, says Tom Hegel, principal threat researcher at the security firm Sentinel One. Hegel has been tracking these malicious domains for more than a year, and he said the seemingly benign software download sites will periodically turn evil, swapping out legitimate copies of popular software titles with backdoored versions that will allow cybercriminals to remotely commander the systems.

“They’re using automation to pull in fake content, and they’re rotating in and out of hosting malware,” Hegel said, noting that the malicious downloads may only be offered to visitors who come from specific geographic locations, like the United States. “In the malicious ad campaigns we’ve seen tied to this group, they would wait until the domains gain legitimacy on the search engines, and then flip the page for a day or so and then flip back.”

In February 2023, Hegel co-authored a report on this same network, which Sentinel One has dubbed MalVirt (a play on “malvertising”). They concluded that the surge in malicious ads spoofing various software products was directly responsible for a surge in malware infections from infostealer trojans like IcedID, Redline Stealer, Formbook and AuroraStealer.

Hegel noted that the spike in malicious software-themed ads came not long after Microsoft started blocking by default Office macros in documents downloaded from the Internet. He said the volume of the current malicious ad campaigns from this group appears to be relatively low compared to a year ago.

“It appears to be same campaign continuing,” Hegel said. “Last January, every Google search for ‘Autocad’ led to something bad. Now, it’s like they’re paying Google to get one out of every dozen of searches. My guess it’s still continuing because of the up-and-down [of the] domains hosting malware and then looking legitimate.”

Several of the websites at this Netherlands host (93.190.143[.]252) are currently blocked by Google’s Safebrowsing technology, and labeled with a conspicuous red warning saying the website will try to foist malware on visitors who ignore the warning and continue.

But it remains a mystery why Google has not similarly blocked more than 240+ other domains at this same host, or else removed them from its search index entirely. Especially considering there is nothing else but these domains hosted at that Netherlands IP address, and because they have all remained at that address for the past year.

In response to questions from KrebsOnSecurity, Google said maintaining a safe ads ecosystem and keeping malware off of its platforms is a priority across Google.

“Bad actors often employ sophisticated measures to conceal their identities and evade our policies and enforcement, sometimes showing Google one thing and users something else,” Google said in a written statement. “We’ve reviewed the ads in question, removed those that violated our policies, and suspended the associated accounts. We’ll continue to monitor and apply our protections.”

Google says it removed 5.2 billion ads in 2022, and restricted more than 4.3 billion ads and suspended over 6.7 million advertiser accounts. The company’s latest ad safety report says Google in 2022 blocked or removed 1.36 billion advertisements for violating its abuse policies.

Some of the domains referenced in this story were included in Sentinel One’s February 2023 report, but dozens more have been added since, such as those spoofing the official download sites for Corel Draw, Github Desktop, Roboform and Teamviewer.

This October 2023 report on the FreeCAD user forum came from a user who reported downloading a copy of the software from freecadsoft[.]com after seeing the site promoted at the top of a Google search result for “freecad.” Almost a month later, another FreeCAD user reported getting stung by the same scam.

“This got me,” FreeCAD forum user “Matterform” wrote on Nov. 19, 2023. “Please leave a report with Google so it can flag it. They paid Google for sponsored posts.”

Sentinel One’s report didn’t delve into the “who” behind this ongoing MalVirt campaign, and there are precious few clues that point to attribution. All of the domains in question were registered through webnic.cc, and several of them display a placeholder page saying the site is ready for content. Viewing the HTML source of these placeholder pages shows many of the hidden comments in the code are in Cyrillic.

Trying to track the crooks using Google’s Ad Transparency tools didn’t lead far. The ad transparency record for the malicious ad featuring freecad-us[.]org (in the screenshot above) shows that the advertising account used to pay for the ad has only run one previous ad through Google search: It advertised a wedding photography website in New Zealand.

The apparent owner of that photography website did not respond to requests for comment, but it’s also likely his Google advertising account was hacked and used to run these malicious ads.