Google Chrome Zero-Day Delivers Memento Spyware

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A zero-day vulnerability in Google Chrome, CVE-2025-2783, was actively exploited in early 2025 by attackers using spyware linked to Memento Labs (formerly Hacking Team), a notorious Italian surveillance. The exploit was used in a campaign dubbed Operation ForumTroll, targeting Russian and Belarusian organizations through phishing emails with short-lived links that triggered a Chrome sandbox escape.

About the Vulnerability

• CVE-2025-2783 is a sandbox escape flaw in Chrome, allowing attackers to break out of browser confinement.
• The exploit leveraged a logic bug in Chromium’s Mojo IPC mechanism, enabling privilege escalation on Windows systems.
• Google patched the vulnerability after disclosure in March 2025, but attacks had already occurred against government, media, and financial entities.

The Espionage Tool: Dante

• Memento Labs’ Dante spyware was delivered via the exploit and represents the successor to the Hacking Team’s “Remote Control Systems” (RCS) kit.
• Dante features advanced anti-analysis, VMProtect obfuscation, and AES-256-CBC encryption; it ties infections to system hardware, detects sandboxes and debugging, and uses modular architecture for surveillance.
• Kaspersky researchers identified unique code and persistence mechanisms linking Dante and the campaign infrastructure, noting strong overlaps with previous Hacking Team operations.
• The campaign also deployed custom malware named LeetAgent in some cases, and code connections tied both toolsets to Memento Labs.

Attribution and Impact

• Memento Labs, rebranded in 2019 after a major breach, maintains offensive cyber capabilities, selling them to governments and corporate clients.
• Analysts warn that flaws in Windows’ DuplicateHandle API enabled the exploit and recommend urgent Chrome updates for enterprise environments.
• The attack campaign may have broader implications for commercial spyware development and international cyber-espionage activities.

Key Indicators and Recommendations

• Look for anomalies related to Chrome sandboxing, suspicious process handle manipulation, and rare persistence methods (COM hijacking, font file data storage).
• Organizations using Chrome or Chromium-based browsers should apply the latest security updates and monitor for the use of obfuscated, modular spyware attributed to Memento Labs.
• The campaign demonstrates ongoing risk from commercial surveillance vendors leveraging zero-days and complex, evasive malware in APT operations.

The CVE-2025-2783 exploit chain targets Chrome’s sandbox protection on Windows, using a vulnerability in the Mojo Inter-Process Communication (IPC) component to escape the browser sandbox and gain code execution on the host system. Below are the core technical details:

Technical Exploit Chain

• Vulnerability Location: Mojo IPC in Chromium (used by Chrome), specifically on Windows before version 134.0.6998.177.
• Flaw Type: Logic error resulting in incorrect handle validation and management.
• Root Cause: Insufficient validation of user-supplied input in Mojo IPC messages from renderer process to browser host, allowing attackers to craft malicious messages triggering unintended behavior outside the sandbox.
• Exploit Steps:

1. Initial Access: Delivered via phishing emails or a malicious site; user clicks a crafted link.
2. Sandbox Escape: Malicious Mojo IPC message sent from compromised renderer leads to a host process returning a privileged handle incorrectly.
3. Code Execution: Attacker escapes sandbox and runs arbitrary code as the browser’s host process, allowing persistence, malware deployment, and lateral movement.

• Chained Exploits: In actual attacks (Operation ForumTroll), CVE-2025-2783 was used as the second stage following a remote code execution (RCE) exploit, maximizing the attacker’s access.
• User Interaction: Exploit requires user action (clicking a malicious link), but no authentication or privilege escalation is needed.

Severity, Scope, and Impact

• Severity: CVSS score ranges from 8.3 to 8.8 (“High”), as it leads to sandbox escape, full system compromise, and possible data exfiltration.
• Scope Change: The exploit allows switching from sandbox context to full host context (scope changed).
• Impact: Attackers can execute arbitrary commands, gain persistence, alter browser/system data, and launch further attacks on the system.

Indicators and Detection

• Anomalous Mojo IPC traffic
• Suspicious handles returned to Chrome renderer
• Malware or persistence mechanisms deployed outside the browser process

MITRE ATT&CK Techniques

• T1203: Exploitation for Client Execution
• T1548: Abuse Elevation Control Mechanism

This flaw affected not just Chrome but any Chromium-based browser on Windows, and rapid updating is required to prevent exploitation.