Fake Claude App Bing Ads Deliver SectopRAT Malware

A fake Claude app promoted through Bing search ads has delivered the SectopRAT remote access trojan to victims through a malicious installer.

Researchers identified at least 29 compromised organisations during the operation, which they track as FakeAgent. The campaign ran between 21 and 22 July and used a malicious Claude Artifact hosted on the legitimate Claude.ai domain.

Malicious Claude Artifact leads to fake installer

The malicious Artifact looked like a software download portal and directed visitors to external websites hosting a file named ClaudeDesktop.exe.

Before Anthropic removed it, researchers said the Artifact had been downloaded around 7,100 times.

The file did not contain a genuine Claude desktop application. Instead, it used a legitimate JetBrains Chromium component to sideload a malicious DLL named libcef.dll.

That DLL installed SectopRAT, also known as ArechClient2, a remote access trojan with information-stealing capabilities.

The campaign also uses another executable named DockerDesktop.exe to create a scheduled task and establish persistence on infected devices.

Malware checks for analysis environments

The infection chain includes several anti-analysis techniques. Its loaders and staging components use VMProtect packing, shader timing checks, GPU and VRAM checks, and virtual-machine detection.

These methods can help attackers identify sandboxed or virtualised environments often used by security researchers. As a result, the malware may avoid executing its full payload during analysis.

SectopRAT has previously appeared in CastleLoader campaigns and ClickFix attacks. The malware uses EtherHiding to retrieve an active command-and-control address through transactions on the Ethereum BNB Smart Chain.

SectopRAT steals credentials and supports remote access

SectopRAT has been active since 2019. It can steal passwords, credit card data, files, browser logins and browser cookies.

The malware also targets FTP credentials, data from messaging applications such as Discord and Telegram, Steam accounts and VPN products.

In addition, SectopRAT includes hidden virtual network computing functionality. This allows attackers to interact with a compromised device remotely and perform hands-on actions in real time.

Researchers used Claude Opus 4.8 during their analysis to assist with shader emulation, cryptographic reconstruction and .NET code review. The decrypted payload pointed to SectopRAT operations or a closely related fork.

Bing ads direct victims to malicious results

The attackers used sponsored Bing search results to direct users towards the fake Claude app download pages.

Researchers also found 10 domains registered to the same email address from December 2025 onward. One domain had previously been linked to StealC distribution and was seized during Operation Endgame.

However, investigators do not have enough evidence to attribute FakeAgent to a known threat group.

Users should download software only from official websites and verified vendor portals. Sponsored search results can lead to convincing but malicious download pages.