Apr 10, 2024NewsroomCyber Crime / Malvertising

Cybersecurity researchers have discovered a new Raspberry Robin campaign wave that propagates the malware through malicious Windows Script Files (WSFs) since March 2024.

“Historically, Raspberry Robin was known to spread through removable media like USB drives, but over time its distributors have experimented with other initial infection vectors,” HP Wolf Security researcher Patrick Schläpfer said in a report shared with The Hacker News.

Raspberry Robin, also called QNAP worm, was first spotted in September 2021 that has since evolved into a downloader for various other payloads in recent years, such as SocGholish, Cobalt Strike, IcedID, BumbleBee, and TrueBot, and also serving as a precursor for ransomware.

While the malware was initially distributed by means of USB devices containing LNK files that retrieved the payload from a compromised QNAP device, it has since adopted other methods such as social engineering and malvertising.

It’s attributed to an emerging threat cluster tracked by Microsoft as Storm-0856, which has links to the broader cybercrime ecosystem comprising groups like Evil Corp, Silence, and TA505.

The latest distribution vector entails the use of WSF files that are offered for download via various domains and subdomains.

It’s currently not clear how the attackers are directing victims to these URLs, although it’s suspected that it could be either via spam or malvertising campaigns.

The heavily obfuscated WSF file functions as a downloader to retrieve the main DLL payload from a remote server using the curl command, but not before a series of anti-analysis and anti-virtual machine evaluations are carried out to determine if it’s being run in a virtualized environment.

It’s also designed to terminate the execution if the build number of the Windows operating system is lower than 17063 (which was released in December 2017) and if the list of running processes includes antivirus processes associated with Avast, Avira, Bitdefender, Check Point, ESET, and Kaspersky.

What’s more, it configures Microsoft Defender Antivirus exclusion rules in an effort to sidestep detection by adding the entire main drive to the exclusion list and preventing it from being scanned.

“The scripts itself are currently not classified as malicious by any an-virus scanners on VirusTotal, demonstrating the evasiveness of the malware and the risk of it causing a serious infection with Raspberry Robin,” HP said.

“The WSF downloader is heavily obfuscated and uses many an-analysis techniques enabling the malware to evade detection and slow down analysis.”

Mar 30, 2024NewsroomMalware / Cryptocurrency

Malicious ads and bogus websites are acting as a conduit to deliver two different stealer malware, including Atomic Stealer, targeting Apple macOS users.

The ongoing infostealer attacks targeting macOS users may have adopted different methods to compromise victims’ Macs, but operate with the end goal of stealing sensitive data, Jamf Threat Labs said in a report published Friday.

One such attack chain targets users searching for Arc Browser on search engines like Google to serve bogus ads that redirect users to look-alike sites (“airci[.]net”) that serve the malware.

“Interestingly, the malicious website cannot be accessed directly, as it returns an error,” security researchers Jaron Bradley, Ferdous Saljooki, and Maggie Zirnhelt said. “It can only be accessed through a generated sponsored link, presumably to evade detection.”

The disk image file downloaded from the counterfeit website (“ArcSetup.dmg”) delivers Atomic Stealer, which is known to request users to enter their system passwords via a fake prompt and ultimately facilitate information theft.

Jamf said it also discovered a phony website called meethub[.]gg that claims to offer a free group meeting scheduling software, but actually installs another stealer malware capable of harvesting users’ keychain data, stored credentials in web browsers, and information from cryptocurrency wallets.

Much like Atomic stealer, the malware – which is said to overlap with a Rust-based stealer family known as Realst – also prompts the user for their macOS login password using an AppleScript call to carry out its malicious actions.

Attacks leveraging this malware are said to have approached victims under the pretext of discussing job opportunities and interviewing them for a podcast, subsequently asking them to download an app from meethub[.]gg to join a video conference provided in the meeting invites.

“These attacks are often focused on those in the crypto industry as such efforts can lead to large payouts for attackers,” the researchers said. “Those in the industry should be hyper-aware that it’s often easy to find public information that they are asset holders or can easily be tied to a company that puts them in this industry.”

The development comes as MacPaw’s cybersecurity division Moonlock Lab disclosed that malicious DMG files (“App_v1.0.4.dmg”) are being used by threat actors to deploy a stealer malware designed to extract credentials and data from various applications.

This is accomplished by means of an obfuscated AppleScript and bash payload that’s retrieved from a Russian IP address, the former of which is used to launch a deceptive prompt (as mentioned above) to trick users into providing the system passwords.

“Disguised as a harmless DMG file, it tricks the user into installation via a phishing image, persuading the user to bypass macOS’s Gatekeeper security feature,” security researcher Mykhailo Hrebeniuk said.

The development is an indication that macOS environments are increasingly under threat from stealer attacks, with some strains even boasting of sophisticated anti-virtualization techniques by activating a self-destructing kill switch to evade detection.

In recent weeks, malvertising campaigns have also been observed pushing the FakeBat loader (aka EugenLoader) and other information stealers like Rhadamanthys via a Go-based loader through decoy sites for popular software such as Notion and PuTTY.

Mar 07, 2024NewsroomVulnerability / Information Stealer

Facebook messages are being used by threat actors to a Python-based information stealer dubbed Snake that’s designed to capture credentials and other sensitive data.

“The credentials harvested from unsuspecting users are transmitted to different platforms such as Discord, GitHub, and Telegram,” Cybereason researcher Kotaro Ogino said in a technical report.

Details about the campaign first emerged on the social media platform X in August 2023. The attacks entail sending prospective users seemingly innocuous RAR or ZIP archive files that, upon opening, activate the infection sequence.

The intermediate stages involve two downloaders – a batch script and a cmd script – with the latter responsible for downloading and executing the information stealer from an actor-controlled GitLab repository.

Cybereason said it detected three different variants of the stealer, the third one being an executable assembled by PyInstaller. The malware, for its part, is designed to gather data from different web browsers, including Cốc Cốc, suggesting a Vietnamese focus.

The collected information, which comprises credentials and cookies, is then exfiltrated in the form of a ZIP archive via the Telegram Bot API. The stealer is also designed to dump cookie information specific to Facebook, an indication that the threat actor is likely looking to hijack the accounts for their own purposes.

The Vietnamese connection is further bolstered by the naming convention of the GitHub and GitLab repositories and the fact that the source code contains references to the Vietnamese language.

“All of the variants support Cốc Cốc Browser, which is a well known Vietnamese Browser used widely by the Vietnamese community,” Ogino said.

Over the past year, multiple information stealers targeting Facebook cookies have appeared in the wild, counting S1deload Stealer, MrTonyScam, NodeStealer, and VietCredCare.

The development comes as Meta has come under criticism in the U.S. for failing to assist victims whose accounts have been hacked into, calling on the company to take immediate action to address a “dramatic and persistent spike” in account takeover incidents.

It also follows a discovery that threat actors are “using a cloned game cheat website, SEO poisoning, and a bug in GitHub to trick would-be-game-hackers into running Lua malware,” according to OALABS Research.

Specifically, the malware operators are leveraging a GitHub vulnerability that allows an uploaded file associated with an issue on a repository to persist even in scenarios where the issue is never saved.

“This means that anyone can upload a file to any git repository on GitHub, and not leave any trace that the file exists except for the direct link,” the researchers said, adding the malware comes fitted with capabilities for command-and-control (C2) communications.

Feb 28, 2024NewsroomPhishing Attack / Malware

Mexican users have been targeted with tax-themed phishing lures at least since November 2023 to distribute a previously undocumented Windows malware called TimbreStealer.

Cisco Talos, which discovered the activity, described the authors as skilled and that the “threat actor has previously used similar tactics, techniques and procedures (TTPs) to distribute a banking trojan known as Mispadu in September 2023.

Besides employing sophisticated obfuscation techniques to sidestep detection and ensure persistence, the phishing campaign makes use of geofencing to single out users in Mexico, returning an innocuous blank PDF file instead of the malicious one if the payload sites are contacted from other locations.

Some of the notable evasive maneuvers include leveraging custom loaders and direct system calls to bypass conventional API monitoring, in addition to utilizing Heaven’s Gate to execute 64-bit code within a 32-bit process, an approach that was also recently adopted by HijackLoader.

The malware comes with several embedded modules for orchestration, decryption, and protection of the main binary, while also running a series of checks to determine if it’s running a sandbox environment, the system language is not Russian, and the timezone is within a Latin American region.

The orchestrator module also looks for files and registry keys to double-check that the machine hasn’t been previously infected, before launching a payload installer component that displays a benign decoy file to the user, as it ultimately triggers the execution of TimbreStealer’s primary payload.

The payload is designed to harvest a wide range of data, including credential information from different folders, system metadata, and the URLs accessed, look for files matching specific extensions, and verify the presence of remote desktop software.

Cisco Talos said it identified overlaps with a Mispadu spam campaign observed in September 2023, although the target industries of TimbreStealer are varied and with a focus on manufacturing and transportation sectors.

The disclosure comes amid the emergence of a new version of another information stealer called Atomic (aka AMOS), which is capable of gathering data from Apple macOS systems such as local user account passwords, credentials from Mozilla Firefox and Chromium-based browsers, crypto wallet information, and files of interest, using an unusual combination of Python and Apple Script code.

“The new variant drops and uses a Python script to stay covert,” Bitdefender researcher Andrei Lapusneanu said, noting the Apple Script block for collecting sensitive files from the victim’s computer exhibits a “significantly high level of similarity” with the RustDoor backdoor.

It also follows the emergence of new stealer malware families such as XSSLite, which was released as part of a malware development competition hosted by the XSS forum, even as existing strains like Agent Tesla and Pony (aka Fareit or Siplog) continued to be used for information theft and subsequent sale on stealer logs marketplaces like Exodus.

Feb 06, 2024NewsroomSocial Engineering / Malvertising

Threat actors are leveraging bogus Facebook job advertisements as a lure to trick prospective targets into installing a new Windows-based stealer malware codenamed Ov3r_Stealer.

“This malware is designed to steal credentials and crypto wallets and send those to a Telegram channel that the threat actor monitors,” Trustwave SpiderLabs said in a report shared with The Hacker News.

Ov3r_Stealer is capable of siphoning IP address-based location, hardware info, passwords, cookies, credit card information, auto-fills, browser extensions, crypto wallets, Microsoft Office documents, and a list of antivirus products installed on the compromised host.

While the exact end goal of the campaign is unknown, it’s likely that the stolen information is offered for sale to other threat actors. Another possibility is that Ov3r_Stealer could be updated over time to act as a QakBot-like loader for additional payloads, including ransomware.

The starting point of the attack is a weaponized PDF file that purports to be a file hosted on OneDrive, urging users to click on an “Access Document” button embedded into it.

Trustwave said it identified the PDF file being shared on a fake Facebook account impersonating Amazon CEO Andy Jassy as well as via Facebook ads for digital advertising jobs.

Users who end up clicking on the button are served an internet shortcut (.URL) file that masquerades as a DocuSign document hosted on Discord’s content delivery network (CDN). The shortcut file then acts as a conduit to deliver a control panel item (.CPL) file, which is then executed using the Windows Control Panel process binary (“control.exe“).

The execution of the CPL file leads to the retrieval of a PowerShell loader (“DATA1.txt”) from a GitHub repository to ultimately launch Ov3r_Stealer.

It’s worth noting at this stage that a near-identical infection chain was recently disclosed by Trend Micro as having put to use by threat actors to drop another stealer called Phemedrone Stealer by exploiting the Microsoft Windows Defender SmartScreen bypass flaw (CVE-2023-36025, CVSS score: 8.8).

The similarities extend to the GitHub repository used (nateeintanan2527) and the fact that Ov3r_Stealer shares code-level overlaps with Phemedrone.

“This malware has recently been reported, and it may be that Phemedrone was re-purposed and renamed to Ov3r_Stealer,” Trustwave said. “The main difference between the two is that Phemedrone is written in C#.”

The findings come as Hudson Rock revealed that threat actors are advertising their access to law enforcement request portals of major organizations like Binance, Google, Meta, and TikTok by exploiting credentials obtained from infostealer infections.

They also follow the emergence of a category of infections called CrackedCantil that take leverage cracked software as an initial access vector to drop loaders like PrivateLoader and SmokeLoader, when subsequently act as a delivery mechanism for information stealers, crypto miners, proxy botnets, and ransomware.

Feb 01, 2024NewsroomCyber Attack / Botnet

The threat actor behind a peer-to-peer (P2P) botnet known as FritzFrog has made a return with a new variant that leverages the Log4Shell vulnerability to propagate internally within an already compromised network.

“The vulnerability is exploited in a brute-force manner that attempts to target as many vulnerable Java applications as possible,” web infrastructure and security company Akamai said in a report shared with The Hacker News.

FritzFrog, first documented by Guardicore (now part of Akamai) in August 2020, is a Golang-based malware that primarily targets internet-facing servers with weak SSH credentials. It’s known to be active since January 2020.

It has since evolved to strike healthcare, education, and government sectors as well as improved its capabilities to ultimately deploy cryptocurrency miners on infected hosts.

What’s novel about the latest version is the use of the Log4Shell vulnerability as a secondary infection vector to specifically single out internal hosts rather than targeting vulnerable publicly-accessible assets.

“When the vulnerability was first discovered, internet-facing applications were prioritized for patching because of their significant risk of compromise,” security researcher Ori David said.

“Contrastly, internal machines, which were less likely to be exploited, were often neglected and remained unpatched — a circumstance that FritzFrog takes advantage of.”

This means that even if the internet-facing applications have been patched, a breach of any other endpoint can expose unpatched internal systems to exploitation and propagate the malware.

The SSH brute-force component of FritzFrog has also received a facelift of its own to identify specific SSH targets by enumerating several system logs on each of its victims.

Another notable change in the malware is use of the PwnKit flaw tracked as CVE-2021-4034 to achieve local privilege escalation.

“FritzFrog continues to employ tactics to remain hidden and avoid detection,” David said. “In particular, it takes special care to avoid dropping files to disk when possible.”

This is accomplished by means of the shared memory location /dev/shm, which has also been put to use by other Linux-based malware such as BPFDoor and Commando Cat, and memfd_create to execute memory-resident payloads.

The disclosure comes as Akamai revealed that the InfectedSlurs botnet is actively exploiting now-patched security flaws (from CVE-2024-22768 through CVE-2024-22772, and CVE-2024-23842) impacting multiple DVR device models from Hitron Systems to launch distributed denial-of-service (DDoS) attacks.

Jan 31, 2024NewsroomCryptocurrency / Cybersecurity

A financially motivated threat actor known as UNC4990 is leveraging weaponized USB devices as an initial infection vector to target organizations in Italy.

Google-owned Mandiant said the attacks single out multiple industries, including health, transportation, construction, and logistics.

“UNC4990 operations generally involve widespread USB infection followed by the deployment of the EMPTYSPACE downloader,” the company said in a Tuesday report.

“During these operations, the cluster relies on third-party websites such as GitHub, Vimeo, and Ars Technica to host encoded additional stages, which it downloads and decodes via PowerShell early in the execution chain.”

UNC4990, active since late 2020, is assessed to be operating out of Italy based on the extensive use of Italian infrastructure for command-and-control (C2) purposes.

It’s currently not known if UNC4990 functions only as an initial access facilitator for other actors. The end goal of the threat actor is not clear, although in one instance an open-source cryptocurrency miner is said to have been deployed after months of beaconing activity.

Details of the campaign were previously documented by Fortgale and Yoroi in early December 2023, with the former tracking the adversary under the name Nebula Broker.

The infection begins when a victim double-clicks on a malicious LNK shortcut file on a removable USB device, leading to the execution of a PowerShell script that’s responsible for downloading EMPTYSPACE (aka BrokerLoader or Vetta Loader) from a remote server via another intermedia PowerShell script hosted on Vimeo.

Yoroi said it identified four different variants of EMPTYSPACE written in Golang, .NET, Node.js, and Python, which subsequently acts as a conduit for fetching next-stage payloads over HTTP from the C2 server, including a backdoor dubbed QUIETBOARD.

A notable aspect of this phase is the use of popular sites like Ars Technica, GitHub, GitLab, and Vimeo for hosting the malicious payload.

“The content hosted on these services posed no direct risk for the everyday users of these services, as the content hosted in isolation was completely benign,” Mandiant researchers said. “Anyone who may have inadvertently clicked or viewed this content in the past was not at risk of being compromised.”

QUIETBOARD, on the other hand, is a Python-based backdoor with a wide range of features that allow it to execute arbitrary commands, alter crypto wallet addresses copied to clipboard to redirect fund transfers to wallets under their control, propagate the malware to removable drives, take screenshots, and gather system information.

Additionally, the backdoor is capable of modular expansion and running independent Python modules like coin miners as well as dynamically fetching and executing Python code from the C2 server.

“The analysis of both EMPTYSPACE and QUIETBOARD suggests how the threat actors took a modular approach in developing their toolset,” Mandiant said.

“The use of multiple programming languages to create different versions of the EMPTYSPACE downloader and the URL change when the Vimeo video was taken down show a predisposition for experimentation and adaptability on the threat actors’ side.”

Jan 16, 2024NewsroomBotnet / Malware

The remote access trojan (RAT) known as Remcos RAT has been found being propagated via webhards by disguising it as adult-themed games in South Korea.

WebHard, short for web hard drive, is a popular online file storage system used to upload, download, and share files in the country.

While webhards have been used in the past to deliver njRAT, UDP RAT, and DDoS botnet malware, the AhnLab Security Emergency Response Center’s (ASEC) latest analysis shows that the technique has been adopted to distribute Remcos RAT.

In these attacks, users are tricked into opening booby-trapped files by passing them off as adult games, which, when launched, execute malicious Visual Basic scripts in order to run an intermediate binary named “ffmpeg.exe.”

This results in the retrieval of Remcos RAT from an actor-controlled server.

A sophisticated RAT, Remcos (aka Remote Control and Surveillance) facilitates unauthorized remote control and surveillance of compromised hosts, enabling threat actors to exfiltrate sensitive data.

This malware, although originally marketed by Germany-based firm Breaking Security in 2016 as a bonafide remote administration tool, has metamorphosed into a potent weapon wielded by adversaries actors to infiltrate systems and establish unfettered control.

“Remcos RAT has evolved into a malicious tool employed by threat actors across various campaigns,” Cyfirma noted in an analysis in August 2023.

“The malware’s multifunctional capabilities, including keylogging, audio recording, screenshot capture, and more, highlight its potential to compromise user privacy, exfiltrate sensitive data, and manipulate systems. The RAT’s ability to disable User Account Control (UAC) and establish persistence further amplifies its potential impact.”