Article
Rhysida Using Oyster Backdoor in Attacks
Threat Actors
In July, the Rhysida ransomware group was observed using the Oyster backdoor malware as part of its attacks. This tactic is part of a broader malvertising campaign first reported in June by security researchers. In this new campaign, fake websites disguised as sites like Microsoft Teams are used to trick users into downloading what they believe are legitimate versions of the software, but instead are malicious installers that drop the Oyster backdoor on the victim’s system.
What’s Notable and Unique
Oyster malware – also known as Broomstick – uses a loader that looks like a legitimate software installer. When a user downloads the loader, the installer deploys the Oyster backdoor, which allows the threat actor to gather information about the victim’s system and steal credentials.
Although researchers observed Rhysida using the Oyster backdoor in an attack in July, Arete has observed the ransomware group using this technique since at least May 2024.
Rhysida is a ransomware-as-a-service (RaaS) that has been active since May 2023, but Arete has observed that the group has been considerably more active in 2024, with a notable spike in activity between June and August. Most recently, the group was responsible for the attack against the Port of Seattle in August, which disrupted systems at Seattle-Tacoma International Airport and resulted in several flight delays.
Analyst Comments
This recent malvertising campaign is a prime example of threat groups actively using search engine optimization (SEO) poisoning to lure victims to legitimate-looking websites and trick them into downloading malware. Although this technique is known to be exploited by a variety of actors, Rhysida has found recent success in using it to gain access to multiple victim systems and will likely continue to do so for as long as it remains effective. Even when using common search engines like Google, it is important that users pay attention to any links that have typos or seem suspicious. Employing active endpoint detection and response solutions is also critical in disrupting threat actor activity and mitigating the risk of a cyber-attack.
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Article
CMS Vulnerability Leads to ClickFix Campaign
Threat actors compromised at least 700 education and technology websites in a recent ClickFix campaign by exploiting a critical SQL injection flaw (CVE-2026-26980) in the Ghost content management system (CMS). Adversaries combined the vulnerability with the ClickFix social engineering tactic to steal admin keys and inject a malicious JavaScript that delivers a fake Cloudflare or CAPTCHA verification pop-up, tricking victims into copying and pasting a malicious command into their systems.
What’s Notable and Unique
Rather than targeting the end user first, this campaign is unique in its initial exploitation of the system, followed by social engineering attempts. This hybrid attack style is likely being leveraged to bypass traditional defenses.
This recent campaign also highlights how trusted web properties can be weaponized at scale and coupled with unpatched CMS vulnerabilities. Rather than using the CMS compromise to perpetrate a single attack, threat actors turned it into a supply-chain attack that ultimately affected over 700 trusted websites.
Analyst Comments
As network defenders and their tools enhance threat detection capabilities, adversaries increasingly seek methods to bypass these defenses. By combining vulnerability exploitation, social engineering techniques, and staging for ancillary attacks, this campaign successfully bypassed traditional defenses and inflicted significant impact. Defending against hybrid cyberattacks requires comprehensive security controls beyond simply patching vulnerabilities. Organizations should focus on limiting movement within the environment, detecting abuse of trusted applications, and preventing end-user manipulation.
Sources
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Article
Threat Actors Leverage Fake JPEG Files for Initial Access
In a recent campaign, researchers observed threat actors using fake JPEG image files as a delivery mechanism to initiate the deployment of additional malicious components. The false JPEG files are typically distributed via phishing emails or other social engineering-based lures, and are actually PowerShell-based malware that deploys a trojanized version of ConnectWise ScreenConnect to establish and maintain persistence in the compromised environment.
What’s Notable and Unique
This campaign leverages JPEG images as the initial lure, where the images are not merely decoys but part of the infection workflow. Victims are typically led to download or open an image that triggers hidden execution logic or redirects them to a payload-delivery sequence that initiates later stages of the intrusion chain.
The attack chain is designed to blend into legitimate environments, making detection more difficult. Execution typically relies on scripted or native Windows components, often including PowerShell or other living-off-the-land binaries, enabling fileless or near-fileless execution and reducing forensic artifacts on disk.
The multistage design ensures that the initial JPEG does not directly contain the full payload but instead triggers retrieval or decryption steps that progressively assemble the final malicious components in memory.
Analyst Comments
This campaign illustrates how threat actors continue to blur the line between legitimate file handling and malicious execution chains, indicating potential overlap with remote management or administrative tooling. The use of JPEG-based staging combined with script-based execution reflects a broader evolution toward a stealth-first intrusion design, in which file formats serve as triggers rather than payload containers.
Sources
OPERATION SILENTCANVAS : JPEG BASED MULTISTAGE POWERSHELL INTRUSION
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