You Don’t Want This Sleepwalker Backdoor on Your Windows Machine

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Security researcher Dominik Reichel uncovered a sophisticated Windows backdoor called Sleepwalker that resides stealthily in memory, waiting for a specific encrypted network packet to activate its unique 23-instruction command language. Disguised as Microsoft’s dpapi.dll and loaded via side-loading into an ESET Management Agent process, Sleepwalker avoids detection by not initiating outbound traffic or listening on network ports, indicating a well-resourced targeted operation rather than opportunistic malware. While many details about its deployment and operators remain unknown, Reichel has released tools and guidance to detect and mitigate the threat.

https://www.theregister.com/security/2026/08/24/you-dont-want-this-sleepwalker-backdoor-on-your-windows-machine/5292021

Malware Can Abuse Windows Hello for Business Keys for Persistent Entra ID Access

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Researcher Dirk-jan Mollema demonstrated that malware running in a logged-in Windows session can abuse Windows Hello for Business keys to authenticate silently to Microsoft Entra ID, enabling persistent cloud access without requiring admin privileges or extracting private keys. This technique leverages Windows ticketing and WebAuthn to request authentication on a compromised device, allowing attackers to register new devices, obtain refresh tokens, and bypass some conditional access controls, exposing limits in phishing-resistant authentication methods. Mollema has released proof-of-concept scripts and recommends monitoring for unexpected device registrations to detect such abuse.

https://thehackernews.com/2026/08/malware-can-abuse-windows-hello-for.html

Claude, Codex, and Hermes Installed Unowned Code Inside Corporate Networks

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Researchers found that AI coding agents like Claude, Codex, and Hermes executed unowned code within corporate networks by following installation commands listed in misconfigured llms.txt files on public websites. These files, intended to guide AI agents, included references to non-existent software packages and domains that attackers could claim to deliver malware, demonstrated by proof-of-concept tests showing real Fortune 500 companies inadvertently ran such code. The findings reveal a critical security gap where AI agents treat third-party documentation as authoritative without verifying it, enabling supply-chain risks and undermining traditional boundaries between data and executable code.

https://arstechnica.com/security/2026/08/claude-codex-and-hermes-installed-unowned-code-inside-corporate-networks/

Hidden Prompts Trick AI Into False Email Summaries

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Researchers at Forcepoint X-Labs demonstrated that attackers can embed hidden HTML prompts in emails to manipulate AI-powered summarizers into producing false information without alerting users. Their proof-of-concept showed altered email summaries with incorrect financial and scheduling details, highlighting the risks of prompt injection attacks on AI systems that process untrusted external content. To mitigate these threats, organizations should separate trusted instructions from untrusted data, verify AI-generated outputs against source content, and enforce strict controls on AI assistant privileges.

https://www.darkreading.com/cyber-risk/hidden-prompts-trick-ai-false-email-summaries

Ransomware Gangs Skip the CEO, Head Straight for the 40-Something IT Manager

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Ransomware attackers are increasingly targeting mid-level managers—particularly 40-something IT managers—rather than CEOs, as these individuals often have significant business access and decision-making authority related to payments and sensitive information. A Zscaler study of 351 victims revealed that nearly two-thirds held managerial roles, primarily in departments like finance, sales, and HR, with attackers using detailed organizational mapping to identify these key targets. This shift reflects a focus on “business privilege” to expedite ransom payments, with campaigns growing more targeted and focused on extortion and data theft rather than indiscriminate encryption.

https://www.theregister.com/security/2026/08/09/ransomware-gangs-skip-the-ceo-head-straight-for-the-40-something-it-manager/5284499

Terabytes of Credentials Leaked in Massive Supply-Chain Attack

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A supply-chain attack on the open-source AI development tool LiteLLM exposed terabytes of credentials from over 2,500 organizations, including major companies like Microsoft, Amazon, Cisco, and Salesforce. Attackers exploited compromised versions of LiteLLM available on the Python Package Index during a 40-minute window in March to scrape sensitive secrets such as cloud keys, SSH keys, and CI/CD pipeline credentials, impacting around 434,000 software pipelines. Security firms CloudSEK and Hudson Rock urge affected organizations to immediately rotate all exposed credentials and audit their environments to mitigate the widespread risk from this incident.

https://arstechnica.com/security/2026/08/terabytes-of-credentials-leaked-in-massive-supply-chain-attack/

Signal Adds an Extra Layer of Security to Make Sure You’re Actually Chatting with the Right Person

Signal has introduced Automatic Key Verification (AKV), a new feature designed to prevent man-in-the-middle attacks by verifying that a contact’s public encryption key matches what Signal’s key transparency system expects. The system maintains an open-source ledger of public keys, audited by third parties like Cloudflare and Trail of Bits, allowing users to automatically verify contact keys if they have the associated phone number. While AKV enhances security by detecting tampering with encryption keys, users still need to actively verify contacts, and the feature requires having the contact's phone number to work effectively.

https://www.theregister.com/security/2026/08/11/signal-adds-an-extra-layer-of-security-to-make-sure-youre-actually-chatting-with-the-right-person/5286461

“Zoomsday” Flaws Could Let One Zoom Participant Attack Another

Researchers discovered three critical vulnerabilities in Zoom’s annotation feature, dubbed “Zoomsday,” that could allow one participant to crash another’s app, leak information, or execute malicious code by sending specially crafted data during meetings. Zoom has released patches addressing these flaws, and users are advised to update promptly, restrict meeting access, and disable unnecessary features to mitigate risk.

https://www.malwarebytes.com/blog/bugs/2026/08/zoomsday-flaws-could-let-one-zoom-participant-attack-another

Cloudflare DDoS Threat Report H1 2026: 1 Tbps Attacks Soar as DNS Floods and Geopolitical Tensions Drive a New Wave

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In the first half of 2026, Cloudflare observed a surge in Distributed Denial of Service (DDoS) attacks exceeding 1 Tbps, driven notably by DNS flood attacks and heightened geopolitical tensions. This trend signals an escalation in large-scale, high-volume cyber threats targeting internet infrastructure, emphasizing the evolving complexity and scale of DDoS attacks in the current digital landscape.

https://blog.cloudflare.com/ddos-threat-report-2026-h1/

Malicious MCP Servers Can Split Instructions to Make AI Coding Agents Exfiltrate Secrets

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Researchers from ASSET Research Group demonstrated that malicious Model Context Protocol (MCP) servers can stealthily exfiltrate sensitive data like SSH keys and source code from AI coding assistants by splitting instructions into innocuous fragments that the agent reconstructs and executes, bypassing straightforward detection. This attack, named GhostSplice, exploits the way AI assistants process tool descriptions and results across multiple interactions, highlighting the need for tighter client-side controls to treat server outputs as data rather than instructions and carefully vet external MCP servers.

https://thehackernews.com/2026/08/malicious-mcp-servers-can-split.html

OpenAI Launches GPT-5.6-Cyber with Reduced Safeguards for Exploit Development

OpenAI has launched GPT-5.6-Cyber, a cybersecurity-specialized AI model with reduced safeguards designed to assist in vulnerability research, penetration testing, and incident response. Available through its Daybreak Red tier to trusted partners, this model improves on previous versions by successfully completing advanced exploit development tasks and detecting high-severity vulnerabilities, though it generates shorter vulnerability reports and has limitations in patch creation. OpenAI emphasizes the importance of providing advanced AI tools to defenders despite risks, as attackers increasingly use AI to accelerate cyberattacks.

https://thehackernews.com/2026/08/openai-launches-gpt-56-cyber-with.html

New Turnkey Kit Makes It Easy for Anyone to Become a Scammer

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A cybercrime actor known as xrep offers a turnkey scam kit that enables individuals with limited technical skills to launch sophisticated cryptocurrency scams, exemplified by a $TSLA token presale fraud. This kit includes a professional-looking phishing website, personalized victim targeting, fake investment dashboards, and an administrative panel for scammers to track and manipulate victims, lowering the barrier to entry for crypto fraud. Victims are lured into revealing their wallet recovery phrases or sending cryptocurrency payments, resulting in irreversible financial losses.

https://www.malwarebytes.com/blog/scams/2026/08/new-turnkey-kit-makes-it-easy-for-anyone-to-become-a-scammer

New Passkey Attacks Can Recover Synced Private Keys or Bypass Phishing-Resistant MFA

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Three recent research efforts revealed attacks bypassing passkey security without breaking underlying cryptography by exploiting implementation flaws in Windows and Google Chrome. These include Windows exposing signed authentication assertions allowing privileged user impersonation (CVE-2026-34348), malware recovering private keys from Google's synced passkeys in Chrome via leaked master secrets, and malware abusing Windows Hello for Business keys without user verification to satisfy phishing-resistant MFA. Microsoft and Google have issued mitigations and updates, but attackers with endpoint access can still leverage these weaknesses, emphasizing the need for endpoint protections and strict enforcement of authentication policies.

https://thehackernews.com/2026/08/new-passkey-attacks-can-recover-synced.html

New CSS Attacks Can Break Webmail Defenses to Steal Passwords and Tokens

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New research presented by PortSwigger reveals novel CSS-based attacks that break webmail security boundaries to steal passwords, tokens, and hijack accounts across major providers like Outlook, Gmail, Yahoo Mail, and Proton Mail. These exploits abuse allowed HTML/CSS features or sanitizer discrepancies to escape email isolation, enabling phishing, token exfiltration, and UI manipulation, with some attacks still functional as of early August 2026. The study recommends sandboxing HTML emails and strict CSS restrictions to mitigate these evolving threats.

https://thehackernews.com/2026/08/new-css-attacks-can-break-webmail.html

UNC6671 Vishing Attacks Target Personal Phones to Steal SaaS Data

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The threat actor group UNC6671 has been conducting vishing attacks targeting personal mobile phones of enterprise employees to steal SaaS credentials and exfiltrate data from cloud environments like Microsoft 365 and Okta. Using social engineering, spoofed help desk calls, and adversary-in-the-middle phishing portals, they intercept login credentials and multi-factor authentication tokens to gain persistent access and lateral movement across SaaS ecosystems. The group operates multiple extortion brands, demands ransoms often negotiated down to hundreds of thousands of dollars, and highlights the necessity of phishing-resistant MFA and vigilant identity provider monitoring to mitigate such risks.

https://thehackernews.com/2026/08/unc6671-vishing-attacks-target-personal.html

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