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BigBear 2.0 phishing campaign hijacks Microsoft 365 sessions after MFA
CloudSEK uncovered BigBear 2.0, a PhaaS operation that captured 4,148 Microsoft 365 session cookies, hijacking authenticated sessions after MFA via AiTM proxy.
CloudSEK infiltrated the BigBear 2.0 phishing-as-a-service panel in June, finding 5,137 credential records tied to 461 organizations in over 40 countries, including 4,148 captured session cookies and 474 completed post-MFA logins. The operation, built on Evilginx2, uses an attacker-controlled reverse proxy to steal authenticated session cookies and residential proxies to defeat location-based Conditional Access checks, while custom code disables FIDO2/WebAuthn on phishing pages. At least five affiliates operated 42 VPS nodes, with IT services and managed service providers the most targeted sector.
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BigBear 2.0 Evilginx2 Phishing Campaign Bypasses Microsoft 365 MFA With Session Cookie Theft
CloudSEK identified BigBear 2.0, an Evilginx2-based AiTM phishing operation stealing Microsoft 365 MFA session cookies, hitting 461 organizations across 40-plus countries.
The campaign proxies Microsoft sign-in pages to capture credentials and authenticated session cookies, enabling session replay into email, Teams, SharePoint, OneDrive, and connected SSO applications. CloudSEK's June 2026 discovery found 5,137 stolen records, 1,032 passwords, and 4,148 session cookies tied to 3,331 victim IPs, linked to operator 'General Boss' across 42 VPS nodes. The operation targeted IT services and managed service providers, used country-matched residential proxies, and involved at least five affiliates.
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Anthropic locks out Claude users after infostealers hijack login sessions
Anthropic invalidated Claude sessions compromised by infostealers such as Vidar, Lumma and Atomic Stealer, which steal browser cookies to bypass 2FA.
Anthropic began locking users out of Claude accounts after infostealer malware stole browser session cookies, letting attackers replay logins and bypass two-factor authentication. Identified malware includes Vidar, Lumma (LummaC2), StealC, RedLine and Acreed on Windows and Atomic Stealer (AMOS) on a small number of Macs. Anthropic signed affected users out, removed saved payment methods and refunded unauthorized charges. One affected user traced the infection to a pirated game downloaded from a Russian underground forum; the company advised victims to remove the malware before resetting passwords and re-enabling 2FA.
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Mirage2FA Surge Hits 4,500 US and EU Companies, Abusing Microsoft 365 Login Flows
Mirage2FA phishing-as-a-service campaign hit ~4,500 organizations, mostly US, stealing Microsoft 365 passwords and session cookies to bypass 2FA.
ANY.RUN research links the Mirage2FA phishing-as-a-service toolkit to 4,532 unique organization email domains between 2024 and 2026, with the US accounting for 63.7% of victims. The kit uses adversary-in-the-middle login flows to harvest credentials and session cookies, bypassing MFA on Microsoft 365 accounts. Researchers recorded more than 9,000 potential compromise events and estimated 48% of targeted email addresses were potentially compromised. Hijacked sessions extend to SSO-connected services, enabling impersonation, fraud and further compromise.
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Impersonating IT support: how threat actors turn a remote session into enterprise-wide access
Microsoft details Teams IT-support impersonation campaigns deploying Node.js implants, AD reconnaissance, and WinRM lateral movement toward domain controllers.
Microsoft Threat Intelligence describes a human-operated campaign where attackers impersonate IT/helpdesk staff via Microsoft Teams external collaboration, talk users into granting remote sessions, and use RMM tools for interactive access. During the session they run PowerShell to silently install a malicious MSI that stages a portable Node.js runtime and obfuscated JavaScript implant for C2, executing follow-on payloads via rundll32. Operators then perform host and Active Directory reconnaissance, capture desktop screenshots, and pivot via WinRM on port 5985 to domain controllers and certificate authorities. The hands-on-keyboard chain, which can precede data theft and ransomware, blends into normal operations by relying on Teams, Quick Assist, msiexec, and Node.js; Microsoft shares hunting and mitigation guidance.
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Passkey-themed social engineering leads to identity and cloud compromise
Microsoft tracks ongoing cloud intrusions where passkey-themed helpdesk lures enable AiTM credential theft, MFA persistence, and SharePoint data theft.
Microsoft Security Research is tracking active cloud-based intrusions, observed since May 2026, that begin with helpdesk impersonation calls and SMS lures urging urgent passkey, MFA, or SSO updates. The lures lead to adversary-in-the-middle phishing or device-code authentication flows that capture credentials and session tokens or grant actor access, after which the actors add authentication methods, conduct Microsoft Graph reconnaissance, and download SharePoint and OneDrive content via REST APIs. Phishing domains embed victim organization names as subdomains (e.g., contoso.add-passkey[.]com), are often registered with Nicenic, and go operational within hours. Microsoft advises revoking sessions and removing unauthorized authentication methods for confirmed compromises.
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CVE-2026-57967: Apache Artemis, Apache ActiveMQ Artemis: Missing authentication on CORE protocol session reattachment
CVE-2026-57967: unauthenticated attackers can hijack authenticated ActiveMQ Artemis sessions via crafted CORE protocol SESSION_REATTACH packets.
An unauthenticated remote attacker can craft a CORE protocol SESSION_REATTACH packet to steal an existing session and assume ongoing execution of the previously authenticated session on Apache Artemis and ActiveMQ Artemis. Affected versions are artemis-server 2.50.0 through 2.56.0 in Apache Artemis and artemis-server 1.0.0 through 2.44.0 in Apache ActiveMQ Artemis. Apache rates the issue important.
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KREMLIN Banking Malware Bypasses Chrome Security to Steal Banking Sessions
Elastic Security Labs details KREMLIN, a Brazilian banking malware that implants malicious Chrome and Edge extensions by forging Chromium integrity values to steal banking sessions.
Elastic Security Labs tracks the KREMLIN banking malware operation as REF9334, active since at least May 2025 across seven campaigns primarily targeting 12 Brazilian banks. The malware is installed by a victim-run JavaScript loader, achieves scheduled-task persistence, and side-loads a malicious DLL via SentinelOne's SentinelMemoryScanner.exe. It modifies Chrome and Edge Secure Preferences files, enables developer mode, and regenerates Chromium MAC values to silently install extensions, while extracting browser encryption material including the newer App-Bound OSCrypt key. An Ethereum smart contract serves as a dead-drop resolver for C2 config; Elastic disrupted over 1,500 infections via a canary domain.
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Hackers Use Passkey-Themed Phishing to Hijack Microsoft 365 Accounts and Steal Cloud Data
Microsoft reports passkey-themed phishing campaigns hijacking Microsoft 365 accounts via AiTM and device-code flows, then exfiltrating cloud data.
Microsoft researchers identified passkey-themed phishing across cloud intrusions observed since May 2026, where callers posing as IT support direct victims to lookalike sign-in pages. The flows include adversary-in-the-middle phishing and device-code authentication, letting attackers capture usable sessions even when MFA succeeds, followed by rogue MFA registration for persistence. Attackers enumerate tenants via Microsoft Graph and collect SharePoint, OneDrive, and Exchange data at rates below 1,000 items per hour; lure domains include passkeyhelpdesk.com and setupmypasskey.com.
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DeepSeek Harness Flaw Let AI Agents Disable Their Own File Sandbox Without Approval
DeepSeek Harness (CVE-2026-82533, CVSS 9.4) let AI coding agents disable their own sandbox via an unauthenticated local API; fixed in 0.1.2-alpha.2.
DeepSeek Harness versions 0.1.1-rc.2 and earlier allowed a sandboxed AI coding agent to turn off its own OS sandbox by calling the tool's unauthenticated local web interface, tracked as CVE-2026-82533 with a 9.4 CVSS from VulnCheck. A single command set the agent session to danger-full-access mode, removing sandboxing and approval prompts, and OX Research verified writes escaped the workspace. The interface trusted the client-supplied Host header with no authentication and could also return a session's entire conversation log. The fix adds a one-time token and signed-cookie check; the first npm release carrying it is 0.1.2-alpha.2, with 0.1.2-rc.1 current.
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BigBear phishing crew nets thousands of Microsoft 365 credentials
CloudSEC accessed the BigBear 2.0 phishing panel, finding 5,137 stolen Microsoft 365 records across 461 organizations, including 474 MFA-bypassed sessions.
CloudSEC researchers got inside the admin panel of BigBear 2.0, an Evilginx2-based phishing-as-a-service operation run by someone known as 'General Boss'. The panel contained 5,137 records tied to 461 organizations: 1,032 plaintext passwords and 4,148 session cookies, with 474 complete MFA-bypassed authentications. The adversary-in-the-middle proxy captures Microsoft 365 session cookies that can be replayed to access email, Teams, SharePoint, and OneDrive, potentially pivoting into Entra ID and federated SaaS. The operation was still active, used custom JavaScript to disable FIDO2/WebAuthn on phishing pages, and routed logins through a residential proxy pool spanning 69 countries.
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The extension you never installed: KREMLIN forges Chrome's own integrity checks to steal banking sessions
Elastic details KREMLIN, a Brazilian banking malware whose malicious Chrome/Edge extension forges Chromium integrity checks to steal sessions.
Elastic Security Labs tracked operation REF9334 and its KREMLIN toolkit, a Brazilian banking malware campaign impersonating twelve banks across seven campaigns since May 2025. The infection chain uses multi-stage obfuscated JavaScript loaders with sandbox checks (file and process counting), scheduled-task persistence, and an Ethereum smart contract acting as a dead-drop resolver for C2 and payload URLs, abusing Archive.org for hosting. The malicious browser extension bypasses Chromium integrity mechanisms by manipulating Secure Preferences and regenerating required HMACs and App-Bound encrypted hashes. Threat Command disrupted over 1,500 infections by registering the kill-switch canary domain.
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Mirage2FA Hijacks Companies’ Microsoft 365 Sessions, with Over 4K Victims in the US
Mirage2FA phishing-as-a-service kit uses AiTM attacks to hijack Microsoft 365 sessions, with over 4,000 US victims.
ANY.RUN analyzed Mirage2FA, an active phishing-as-a-service toolkit that steals Microsoft 365 credentials and authenticated sessions through Adversary-in-the-Middle phishing pages. About 63.7% of identified victims are in the US, with Technology, Manufacturing, and Education the most targeted industries. Thousands of compromise events were recorded between 2024 and 2026.
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KREMLIN Banking Malware Hijacks Chrome and Edge to Steal Credentials and Session Tokens
Elastic Security Labs details KREMLIN, Brazilian banking malware using malicious Chrome/Edge extensions and Ethereum smart contracts to steal credentials and session tokens.
Elastic Security Labs documents KREMLIN (tracked as REF9334), a Brazilian banking malware toolkit active since at least May 2025 that impersonates a dozen Brazilian banks. It uses multi-stage JavaScript loaders, a C++ installer that DLL-sideloads via a legitimate SentinelOne binary, and a malicious Chrome/Edge extension named 'AVSync System Inc.' Ethereum smart contracts act as dead-drop resolvers for C2 endpoints, a shift that occurred May 19, 2026, making infrastructure hard to disrupt. The extension harvests cookies, sessionStorage/localStorage, browsing history, screenshots, and full page HTML via WebSocket plus CSS-disguised polling endpoints. The group has run seven distinct campaigns and also distributes Pulsar RAT and Remcos RAT.
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