All news with #backdoor found tag

Russian APT Uses Hyper‑V VMs for Stealth and Persistence

🛡️ Bitdefender researchers describe how the Russia-aligned APT group Curly COMrades enabled Windows Hyper-V to deploy a minimal Alpine Linux VM on compromised Windows 10 hosts, creating a hidden execution environment. The compact VM (≈120MB disk, 256MB RAM) hosted two libcurl-based implants, CurlyShell (reverse shell) and CurlCat (HTTP-to-SSH proxy), enabling C2 and tunneling that evaded many host EDRs. Attackers used DISM and PowerShell to enable and run the VM under the deceptive name "WSL," and also employed PowerShell and Group Policy for credential operations and Kerberos ticket injection. Bitdefender warns that VM isolation can bypass EDR and recommends layered defenses including host network inspection and proactive hardening.

GTIG: Threat Actors Shift to AI-Enabled Runtime Malware

🔍 Google Threat Intelligence Group (GTIG) reports an operational shift from adversaries using AI for productivity to embedding generative models inside malware to generate or alter code at runtime. GTIG details “just-in-time” LLM calls in families like PROMPTFLUX and PROMPTSTEAL, which query external models such as Gemini to obfuscate, regenerate, or produce one‑time functions during execution. Google says it disabled abusive assets, strengthened classifiers and model protections, and recommends monitoring LLM API usage, protecting credentials, and treating runtime model calls as potential live command channels.

OpenAI Assistants API Abused by 'SesameOp' Backdoor

🔐 Microsoft Incident Response (DART) uncovered a covert backdoor named 'SesameOp' in July 2025 that leverages the OpenAI Assistants API as a command-and-control channel. The malware uses an obfuscated DLL loader, Netapi64.dll, and a .NET component, OpenAIAgent.Netapi64, to fetch compressed, encrypted commands and return results via the API. Microsoft recommends firewall audits, EDR in block mode, tamper protection and cloud-delivered Defender protections to mitigate the threat.

Russian Hackers Hide Malware in Hyper‑V Alpine Linux VMs

🛡️The Russian-linked threat group Curly COMrades abused Microsoft Hyper-V on Windows hosts to deploy a hidden, minimal Alpine Linux VM that hosted custom implants: CurlyShell (reverse shell) and CurlCat (reverse proxy). By using the Hyper-V Default Switch and naming the VM "WSL," outbound C2 traffic appeared to originate from the legitimate host IP, enabling evasion of host-based EDRs. The campaign — active since mid-2024 and observed by Bitdefender with help from the Georgian CERT — also employed PowerShell scripts for LSASS Kerberos ticket injection and Group Policy-based account creation, leaving few forensic traces. Organizations are advised to monitor unexpected Hyper-V activation, abnormal LSASS access or tampering, PowerShell GPO deployments, and to implement network-level inspection and layered defenses.

SesameOp Backdoor Abuses OpenAI Assistants API for C2

🛡️ Researchers at Microsoft disclosed a previously undocumented backdoor, dubbed SesameOp, that abuses the OpenAI Assistants API to relay commands and exfiltrate results. The attack chain uses .NET AppDomainManager injection to load obfuscated libraries (loader "Netapi64.dll") into developer tools and relies on a hard-coded API key to pull payloads from assistant descriptions. Because traffic goes to api.openai.com, the campaign evaded traditional C2 detection. Microsoft Defender detections and account key revocation were used to disrupt the operation.

Operation SkyCloak: Tor-Enabled Backdoor Targets Defense

🔒 Attackers are deploying a persistent backdoor using OpenSSH and a customized Tor hidden service to target defense-related organizations in Russia and Belarus. The Operation SkyCloak campaign uses weaponized ZIP attachments and LNK-triggered PowerShell stagers that perform sandbox evasion and write an .onion hostname into the user's roaming profile. Persistence is established via scheduled tasks that run a renamed sshd.exe and a bespoke Tor binary using obfs4, enabling SSH, SFTP, RDP and SMB access over Tor.

Rhysida Ransomware Abuses Microsoft Code-Signing Trust

🔒Rhysida, a known enterprise-focused ransomware gang, is distributing malware via malvertising on Microsoft's Bing that redirects users to fake download pages for common tools such as Microsoft Teams, PuTTY, and Zoom. Victims who download receive an initial access trojan called OysterLoader, which establishes a persistent backdoor and is signed with Microsoft-like certificates to appear legitimate. The campaign pairs obfuscation/packing to lower static detection with trusted code signing to bypass allow-lists and AV. Experts urge behavior-based EDR, certificate pinning, DNS filtering, and tighter certificate oversight.

Microsoft Detects SesameOp Backdoor Using OpenAI API

🔒 Microsoft’s Detection and Response Team (DART) detailed a novel .NET backdoor called SesameOp that leverages the OpenAI Assistants API as a covert command-and-control channel. Discovered in July 2025 during a prolonged intrusion, the implant uses a loader (Netapi64.dll) and an OpenAIAgent.Netapi64 component to fetch encrypted commands and return execution results via the API. The DLL is heavily obfuscated with Eazfuscator.NET and is injected at runtime using .NET AppDomainManager injection for stealth and persistence.

Fake Solidity VSCode Extension on Open VSX Backdoors

🛡️ A remote-access trojan named SleepyDuck, disguised as a Solidity extension on Open VSX, uses an Ethereum smart contract to deliver command-and-control instructions. The malicious package, downloaded over 53,000 times, activates on editor startup, when a Solidity file is opened, or when the compile command is run. On activation it collects system identifiers, creates a lock file for persistence, and polls an on-chain contract to update or replace its C2 endpoint. Open VSX has flagged the package and implemented security controls; developers should rely only on reputable publishers and official repositories.

SesameOp Backdoor Uses OpenAI Assistants API Stealthily

🔐 Microsoft security researchers identified a new backdoor, SesameOp, which abuses the OpenAI Assistants API as a covert command-and-control channel. Discovered during a July 2025 investigation, the backdoor retrieves compressed, encrypted commands via the API, decrypts and executes them, and returns encrypted exfiltration through the same channel. Microsoft and OpenAI disabled the abused account and key; recommended mitigations include auditing firewall logs, enabling tamper protection, and configuring endpoint detection in block mode.

Malicious VSX Extension 'SleepyDuck' Uses Ethereum

🦆 Researchers at Secure Annex warned of a malicious Open VSX extension, juan-bianco.solidity-vlang, that delivers a remote access trojan dubbed SleepyDuck. Originally published as a benign library on October 31, 2025, it was updated to a malicious release after reaching about 14,000 downloads. The extension triggers on opening a code editor window or selecting a .sol file, harvesting host details and polling an Ethereum-based contract to obtain and update its command server. It also contains fallback logic using multiple Ethereum RPC providers to recover C2 information if the domain is taken down; users should only install extensions from trusted publishers and follow vendor guidance.

SesameOp backdoor abuses OpenAI Assistants API for C2

🛡️ Microsoft DART researchers uncovered SesameOp, a novel .NET backdoor that leverages the OpenAI Assistants API as a covert command-and-control (C2) channel instead of traditional infrastructure. The implant includes a heavily obfuscated loader (Netapi64.dll) and a backdoor (OpenAIAgent.Netapi64) that persist via .NET AppDomainManager injection, using layered RSA/AES encryption and GZIP compression to fetch, execute, and exfiltrate commands. Microsoft and OpenAI investigated jointly and disabled the suspected API key; detections and mitigation guidance are provided for defenders.

Generative AI Speeds XLoader Malware Analysis and Detection

🔍 Check Point Research applied generative AI to accelerate reverse engineering of XLoader 8.0, reducing days of manual work to hours. The models autonomously identified multi-layer encryption routines, decrypted obfuscated functions, and uncovered hidden command-and-control domains and fake infrastructure. Analysts were able to extract IoCs far more quickly and integrate them into defenses. The AI-assisted workflow delivered timelier, higher-fidelity threat intelligence and improved protection for users worldwide.

Rhysida Ransomware Uses Microsoft Signing to Evade Defenses

🛡️ Rhysida ransomware operators have shifted to malvertising and the abuse of Microsoft Trusted Signing certificates to slip malware past defenses. By buying Bing search ads that point to convincing fake download pages for Microsoft Teams, PuTTY and Zoom, they deliver initial access tools such as OysterLoader (formerly Broomstick/CleanUpLoader) and Latrodectus. Signed, packaged binaries evade static detection and often run without scrutiny on Windows endpoints.

HttpTroy Backdoor Poses as VPN Invoice in Kimsuky Attack

🔒 Security researchers at Gen Digital disclosed a targeted Kimsuky campaign that delivered a previously undocumented backdoor called HttpTroy, hidden inside a ZIP attachment masquerading as a VPN invoice. The multi-stage chain used a Golang dropper, a loader dubbed MemLoad and a DLL backdoor executed via a scheduled task named "AhnlabUpdate" to achieve persistence. HttpTroy provides extensive remote-control capabilities and communicates with a C2 server over HTTP, while employing layered obfuscation to hinder analysis and detection.

ASD Warns of Ongoing BADCANDY Attacks on Cisco IOS XE

🛡️ The Australian Signals Directorate (ASD) has issued a bulletin warning of ongoing attacks using a Lua-based implant dubbed BADCANDY to compromise unpatched Cisco IOS XE devices via CVE-2023-20198. ASD reports variations have been seen since October 2023 and estimates about 400 Australian devices were compromised since July 2025, with 150 infections in October. Operators are urged to apply patches, restrict public access to the web UI, and follow Cisco hardening guidance.

Chinese Hackers Exploit Hard-to-Patch Windows Shortcut Flaw

🛡️Arctic Wolf reports that Chinese government-linked actors, tracked as UNC6384 and linked to the longer-running Mustang Panda cluster, conducted spear-phishing campaigns in September and October targeting diplomats in Hungary, Belgium, Serbia, Italy and the Netherlands by abusing a long-known Windows .LNK shortcut parsing flaw. The vulnerability allows command-line instructions to be concealed in .LNK whitespace so attackers can display decoy PDFs—such as an agenda for a European Commission meeting—while executing payloads that deploy the PlugX remote-access Trojan. Trend Micro and ZDI previously documented the issue (i.e., ZDI-CAN-25373, later CVE-2025-9491), but Microsoft has so far declined to fully patch it; Arctic Wolf advises blocking or disabling .LNK execution, monitoring for related binaries like cnmpaui.exe, and blocking C2 domains as interim mitigations.

Australia warns of BadCandy infections on Cisco devices

⚠️ The Australian Signals Directorate warns of ongoing attacks against unpatched Cisco IOS XE devices being backdoored with the Lua-based BadCandy webshell. The exploited flaw, CVE-2023-20198, allows unauthenticated actors to create local admin accounts via the web UI and execute commands with root privileges. Cisco issued a patch in October 2023, but many internet-exposed devices remain vulnerable and have been repeatedly re-infected.

China-linked Tick exploits Lanscope flaw to deploy backdoor

⚠️ Sophos and JPCERT/CC have linked active exploitation of a critical Motex Lanscope Endpoint Manager vulnerability (CVE-2025-61932, CVSS 9.3) to the China-aligned Tick group. Attackers leveraged the flaw to execute SYSTEM-level commands and drop a Gokcpdoor backdoor, observed in both server and client variants that create covert C2 channels. The campaign used DLL side-loading to run an OAED Loader, deployed the Havoc post-exploitation framework on select hosts, and used tools like goddi and tunneled Remote Desktop for lateral movement. Organizations are advised to upgrade or isolate internet-facing LANSCOPE servers and review deployments of the MR and DA agents.

PhantomRaven: Malware in 126 npm Packages Steals Tokens

⚠️ Koi Security has identified a supply-chain campaign dubbed PhantomRaven that inserted malicious code into 126 npm packages, collectively installed more than 86,000 times, by pointing dependencies to an attacker-controlled host (packages.storeartifact[.]com). The packages include preinstall lifecycle hooks that fetch and execute remote dynamic dependencies, enabling immediate execution on developers' machines. The payloads are designed to harvest GitHub tokens, CI/CD secrets, developer emails and system fingerprints, and exfiltrate the results, while typical scanners and dependency analyzers miss the remote dependencies because npmjs.com does not follow those external URLs.