Microsoft

Microsoft reports that Storm-3168, which it links to the JADEPUFFER operator Sysdig described as agentic ransomware, used two compromised service principals to enumerate an Azure tenant, then attempted more than 150 destructive or credential-collection operations in 35 minutes, deleting most targeted storage accounts along with a Key Vault and Function App. Microsoft says the timing and division of work strongly indicate automated or scripted execution; it did not observe a ransom note or confirm exfiltration.

Microsoft reports a campaign between August 3 and 5, 2026 that sent more than a million emails impersonating company executives to push accounts-payable staff toward an ACH payment of nearly $50,000, backed by fabricated invoices and forwarded threads impersonating ServiceNow. Microsoft says the templates showed multiple indicators consistent with generative AI, though these do not establish how much of the content AI produced.

Varonis Threat Labs chained URL-parameter prompt injection with an auto-run behavior in Microsoft Copilot Personal so that a single click on a Copilot link could make it read and leak email, calendar, file metadata, chat history and memory from connected accounts. Varonis disclosed in December 2025, Microsoft patched on 2026-08-18, and Varonis saw no in-the-wild exploitation.

Anthropic reports that about 50 Glasswing partners used Claude Mythos Preview to find more than ten thousand high- or critical-severity vulnerabilities, and that its own scan of over 1,000 open-source projects produced 6,202 model-estimated high/critical findings. Of 1,752 assessed, mostly by six independent firms, 90.6% were true positives; Anthropic estimates 530 high/critical bugs disclosed, of which 75 were patched, and says triage and patching capacity, not discovery, is the bottleneck.

Microsoft's Defender security research team described two vulnerabilities in its open-source Semantic Kernel agent framework in which attacker-influenced prompts could reach code execution on the host. One involved unsafe string interpolation in an in-memory vector store filter; the other exposed a code-execution plugin function that allowed arbitrary file writes outside its sandbox. Both were fixed in updated SDK releases.

Microsoft researchers red-teamed an internal platform of over 100 always-on LLM agents that represent different people and interact through forums, messages and a marketplace. They describe four network-level failure modes: self-propagating messages, amplification of false claims, capture of reputation and verification systems, and hard-to-trace flows through unwitting intermediaries. A small share of agents spontaneously adopted protective behaviors that spread through the network.

Anthropic launched Project Glasswing with AWS, Apple, Broadcom, Cisco, CrowdStrike, Google, JPMorganChase, the Linux Foundation, Microsoft, NVIDIA and Palo Alto Networks to use the unreleased Claude Mythos Preview for defensive security work, extending access to over 40 more organizations that maintain critical software. Anthropic committed up to $100M in usage credits and $4M in donations to open-source security groups, and reports Mythos Preview found thousands of high-severity vulnerabilities, including in every major operating system and browser.

CTI-REALM places agents in a tool-rich environment where they read threat intelligence reports, explore telemetry, iterate KQL queries and produce Sigma and KQL detection rules across Linux, AKS and Azure cloud scenarios. The paper's evaluation of 16 model configurations found Claude Opus 4.6 (High) best at 0.637, with cloud detection hardest; Microsoft's blog later added an early Claude Mythos Preview snapshot scoring 0.685.

Researchers led by Georgia Tech released OSS-CRS, a locally deployable framework for running and combining AIxCC cyber reasoning systems, noting that all seven open-sourced finalist systems depended on competition cloud infrastructure that no longer exists. Porting the winning Atlantis system, they found 10 previously unknown bugs (three high severity) in 8 OSS-Fuzz projects; OpenSSF welcomed OSS-CRS into its AI/ML Security Working Group in April 2026.

Microsoft reports a randomized controlled trial of its own Security Copilot Phishing Triage Agent. In the trial, 167 external security analysts each triaged a 25-email queue drawn from a curated corpus of emails reported by Microsoft employees. In the scenario where the agent classified every corpus email correctly, analysts with the agent found 6.5 times as many true positives per minute as the control group and scored 77% higher on F1; with the agent's accuracy set to 80% and a 20% malicious rate, the productivity gain fell to 3.1 times. Analysts with the agent spent 53% more time on malicious emails and did not simply confirm its malicious verdicts, but they were more likely to accept its benign verdicts, including planted false negatives.

Johann Rehberger showed that injected instructions in project content could make GitHub Copilot in VS Code edit workspace settings to switch off command confirmations, after which it could run arbitrary terminal commands. He reported it on 2025-06-29 and Microsoft patched it in the August 2025 Patch Tuesday.

DARPA reports that seven finalist cyber reasoning systems analyzed over 54 million lines of code, found 54 unique synthetic vulnerabilities in 63 challenges and patched 43, and found 18 real non-synthetic vulnerabilities with 11 patches. Team Atlanta won $4 million, Trail of Bits $3 million and Theori $1.5 million; DARPA and ARPA-H added $1.4 million for real-world integration and four systems were open-sourced on the day.

Zenity Labs presented at Black Hat USA 2025 a set of zero- and one-click prompt injection chains, including a shared document causing ChatGPT Connectors to search a victim's Google Drive for API keys and leak them through image rendering, and a poisoned email steering a Copilot Studio agent to disclose CRM data. CSO Online reports that OpenAI and Microsoft deployed fixes for the specific demonstrated techniques.

Microsoft Research describes Project Ire, a prototype LLM agent that uses decompilers and binary analysis tools to reverse engineer software and classify it as malicious or benign, producing an auditable chain-of-evidence report. Microsoft reports 0.98 precision and 0.83 recall on a Windows driver dataset, but 0.26 recall on about 4,000 hard real-world files, and plans to deploy it in Defender as Binary Analyzer.

ExCyTIn-Bench builds threat-investigation questions from graphs of security logs collected in a controlled Azure tenant with simulated multi-step attacks, and asks agents to query the logs to answer them. In the July 2025 version the best model (o4-mini) reached a reward of 0.368; in the May 2026 revision, accepted at ICML 2026, the best (Claude Opus 4.5) reached 0.606, which the authors say leaves substantial headroom.

Aim Labs disclosed a zero-click chain in which an email containing hidden instructions, once retrieved by Microsoft 365 Copilot, could cause Copilot to embed internal data in an auto-loaded image request to an attacker. Microsoft rated CVE-2025-32711 critical, fixed it server-side in May 2025, and stated there was no evidence of real-world exploitation.

Microsoft researchers and collaborators report on LLMail-Inject, a public challenge in which participants tried to inject instructions into emails to trigger unauthorized tool calls by an LLM email assistant protected by various defenses. The released dataset contains 208,095 unique attack submissions from 839 participants across multiple defenses, models and retrieval configurations.

Authors from Invariant Labs, IBM, ETH Zurich, Swisscom, Google, Microsoft and others propose six design patterns that limit what injected text can do, such as action-selector, plan-then-execute, dual LLM, LLM map-reduce, code-then-execute and context minimization. They discuss utility and security trade-offs and illustrate the patterns with ten application case studies.

Microsoft announced Microsoft-built Security Copilot agents, including a Phishing Triage Agent in Defender, alert triage agents in Purview, a Conditional Access Optimization Agent, a Vulnerability Remediation Agent in Intune and a Threat Intelligence Briefing Agent, plus five partner agents. Preview was planned from April 2025; the announcement contains no evaluation of agent accuracy.

Hines and colleagues at Microsoft describe spotlighting, a family of prompt-engineering transformations (delimiting, datamarking, encoding) that signal to the model where untrusted text came from. On GPT-family models they report attack success falling from above 50% to under 2% with minimal task impact. Microsoft later described spotlighting as one layer of its production defense-in-depth.

Microsoft Threat Intelligence, publishing jointly with OpenAI, describes five state-affiliated actors from Russia, North Korea, Iran and China using LLMs for tasks such as research, scripting help and drafting phishing content. Microsoft says it and OpenAI had not seen novel or unique AI-enabled attack techniques, and that assets and accounts associated with the actors were disrupted.

Microsoft economists ran randomized controlled trials in which novices and security professionals completed incident summarization, script analysis, incident report and guided response tasks in a Defender XDR test environment, with half given Security Copilot. The January 2024 revision reports that novices with Copilot answered 35% more questions correctly and professionals were 7% more accurate, with both groups completing tasks faster.

At Black Hat USA 2023, DARPA announced the AI Cyber Challenge (AIxCC), a two-year competition to build AI-driven systems that automatically find and fix vulnerabilities in critical open-source software. Anthropic, Google, Microsoft and OpenAI agreed to provide technology and expertise to competitors, OpenSSF served as challenge advisor, and semifinal and final rounds were scheduled for DEF CON 2024 and 2025.