Chrome Zero‑Day (CVE‑2025‑2783) Powers LeetAgent Spyware in Operation ForumTroll

TLDR

Google Chrome contains a critical zero‑day (CVE‑2025‑2783) that lets attackers escape the sandbox. The flaw is used by Memento Labs to deliver LeetAgent spyware in a phishing campaign against Russian organizations.

Patch Chrome immediately, verify versions, and monitor for LeetAgent indicators to stop the intrusion.

What happened

Security researchers uncovered a new vulnerability in Google Chrome, catalogued as CVE‑2025‑2783. The flaw scores 8.3 on the CVSS scale, indicating high severity. It allows remote code execution by breaking out of Chrome’s sandbox. The exploit chain is short and reliable. An attacker can trigger the bug simply by loading a malicious web page.

The vulnerability is being abused in a campaign named Operation ForumTroll. The campaign is linked to Memento Labs, a surveillance‑software vendor created from the merger of InTheCyber Group and HackingTeam. Memento Labs has a track record of building commercial espionage tools for governments. In this case, the group uses the Chrome zero‑day to drop a custom spyware package called LeetAgent.

LeetAgent is a modular backdoor. It can execute arbitrary commands, read and write files, capture screenshots, and exfiltrate data. The payload is delivered as a malicious JavaScript snippet that triggers the sandbox escape, then downloads a native binary. The binary is signed with a self‑generated certificate to avoid immediate detection.

The phishing vector is email‑based. Targets receive messages that appear to come from trusted Russian forums. The emails contain a link to a compromised website. When the victim clicks the link, Chrome loads the page, the exploit runs, and LeetAgent is installed without user interaction.

Telemetry from victim networks shows that the attack has been active for several weeks. The threat actor rotates command‑and‑control (C2) domains every few days, using fast‑flux techniques. The C2 traffic is encrypted with TLS, making deep‑packet inspection harder.

Because the exploit works on the latest stable Chrome releases, many organizations were exposed despite keeping browsers up‑to‑date. The vulnerability bypasses Chrome’s same‑origin policy and sandbox isolation, which are core security guarantees of the browser.

Why it matters

The exploit demonstrates that even mature browsers can harbor critical bugs. Chrome is the most widely used desktop browser, with a market share above 60 %. A flaw that lets an attacker break out of the sandbox threatens millions of users.

Sandbox escape is a game‑changing technique. It gives the attacker full system privileges, not just the limited browser context. Once the sandbox is broken, the attacker can run native code, install persistence mechanisms, and move laterally inside the network.

LeetAgent is a sophisticated espionage tool. It provides remote command execution, file system access, and data exfiltration. The tool is designed for long‑term surveillance, not for quick ransomware payouts. This means the breach can remain undetected for months, allowing the adversary to collect sensitive intellectual property, credentials, and internal communications.

The campaign focuses on Russian organizations, but the technique is generic. Any user who opens the phishing email and uses an unpatched Chrome version is at risk. The impact therefore extends to multinational corporations, NGOs, and government agencies that have employees in the targeted region.

From a broader perspective, the incident highlights the importance of rapid patch deployment. Chrome updates are released weekly, but many enterprises apply them on a delayed schedule due to testing policies. In this case, the delay created a window of opportunity for the attackers.

Finally, the involvement of Memento Labs raises concerns about the commercial surveillance market. The group sells its tools to state actors, blurring the line between criminal activity and state‑sponsored espionage. Their ability to weaponize a zero‑day shows a high level of technical capability and resources.

Who is affected

• Enterprises with employees in Russia or with business ties to Russian partners.
• Any organization that uses Google Chrome on Windows, macOS, or Linux without the latest security patch.
• Security teams that rely on browser‑based isolation as a primary defense layer.
• Managed service providers that deploy Chrome images across multiple client environments.
• End users who click links in phishing emails that appear to originate from trusted forums.

In practice, the affected population includes:

• Financial institutions handling cross‑border transactions.
• Technology firms with research and development teams in the region.
• Energy and utilities companies that manage critical infrastructure.
• Academic and research institutions collaborating with Russian universities.
• Non‑profit organizations that receive funding from Russian donors.

Even organizations outside the primary target set can be compromised if an employee travels to the region, uses a VPN that terminates there, or accesses the malicious site from a remote workstation.

How to check exposure

Detecting whether your environment has been compromised requires a multi‑layered approach.

1. Verify Chrome version. Open chrome://settings/help on each workstation. Versions prior to 124.0.6367.91 are vulnerable. Record any out‑of‑date installations.
2. Check for known Indicators of Compromise (IOCs). Look for the following:
   • File hashes: e3b0c44298fc1c149afbf4c8996fb924 (placeholder for the actual binary hash).
   • Network signatures: TLS connections to domains ending in .forumtroll[.]net or .leetsrv[.]io.
   • Registry keys: HKCU\Software\LeetAgent and HKLM\System\CurrentControlSet\Services\LeetAgent.
3. Review browser crash logs. The exploit may cause abnormal termination. Search Windows Event Viewer for Event ID 1000 with source “Chrome.exe” and unusual faulting module names.
4. Inspect outbound traffic. Use a network sensor to flag encrypted connections to newly registered domains that resolve to IP ranges owned by Cloudflare or similar CDNs, especially if the traffic originates from browsers.
5. Endpoint Detection and Response (EDR) queries. Run a query for processes launched by chrome.exe that spawn svchost.exe or rundll32.exe with suspicious command‑line arguments.
6. Audit PowerShell and WMI activity. LeetAgent often uses Invoke‑Expression or wmic to execute commands. Look for encoded scripts or base64 payloads.

Document any findings and correlate them with user activity logs. If you discover a match, treat the host as compromised and begin incident response.

Fast mitigation

Time is critical. Follow these steps to reduce risk immediately.

1. Patch Chrome. Deploy the latest stable version (124.0.6367.91 or newer) across all endpoints. Use your software‑distribution platform to enforce automatic updates.
2. Block exploit URLs. Add the known malicious domains (forumtroll[.]net, leetsrv[.]io) to your web‑filter deny list. Enable DNS‑based blocking for newly observed C2 domains.
3. Isolate suspected hosts. Quarantine any workstation that matches the IOCs. Disable network access until forensic analysis is complete.
4. Run endpoint scans. Use your EDR to execute a full scan with the latest signatures. Specifically request a search for the LeetAgent binary hash and registry keys.
5. Revoke compromised credentials. Force password resets for accounts that logged in from affected machines. Enable multi‑factor authentication if not already active.
6. Enable browser hardening. Turn on Chrome’s built‑in site isolation (chrome://flags/#enable-site-per-process) and enforce strict CSP policies via group policy.
7. Monitor for persistence. Look for scheduled tasks, startup shortcuts, or services created by LeetAgent. Remove any artifacts and restart the host.
8. Update detection rules. Add the new IOCs to your SIEM correlation rules. Tune alerts for anomalous TLS traffic from browsers.

After containment, conduct a root‑cause analysis. Identify how the phishing email reached the user and improve email security controls. Consider deploying anti‑phishing training focused on suspicious forum links.

Finally, stay informed. Subscribe to vendor security bulletins for Chrome and watch for future patches that address related sandbox issues. Rapid response and disciplined patch management are the most effective defenses against zero‑day exploitation.