CVE-2024-39338: Active Exploitation of Marimo Pre-Auth RCE — Defense & Remediation

Security teams utilizing Marimo, the open-source reactive notebook for Python, are facing a critical threat. A vulnerability tracked as CVE-2024-39338 is currently under active exploitation in the wild. This pre-authentication remote code execution (RCE) flaw allows unauthenticated attackers to execute arbitrary commands on the server hosting the Marimo notebook environment. Initial intelligence indicates attackers are leveraging this flaw specifically for credential theft and lateral movement.

Executive Summary

• Vulnerability: CVE-2024-39338 (CVSS 9.8 Critical)
• Affected Component: Marimo Notebook Server (versions prior to 0.8.19)
• Impact: Unauthenticated RCE, credential theft, server takeover.
• Status: Active Exploitation Confirmed.

If your organization runs Marimo notebooks—particularly those exposed to the internet or accessible via inbound tunnels—you must assume breach until patches are verified.

Technical Analysis

The Flaw (CVE-2024-39338) Marimo is designed as an interactive notebook tool often used for data science and engineering workflows. It runs a local web server (typically binding to 0.0.0.0 or localhost via port forwarding) to render the UI. The vulnerability stems from insufficient validation of serialized data or specifically crafted notebook files/requests processed by the server backend.

In versions prior to 0.8.19, an attacker can send a malicious request to the Marimo server endpoint without requiring any authentication. The server processes this input and deserializes or executes it, leading to arbitrary code execution with the privileges of the user running the Marimo process.

Attack Chain & Exploitation Status

1. ** Reconnaissance:** Attackers scan for Marimo instances, often detecting distinct HTTP headers or UI fingerprints (e.g., /marimo paths) on exposed ports (default 2718).
2. Exploitation: A single unauthenticated HTTP request triggers the vulnerability, spawning a shell or executing Python code on the host.
3. Credential Theft: Because notebooks often contain access keys, database connection strings, and AWS/Azure credentials, the primary goal of observed exploitation is immediate scraping of environment variables (.env files) and notebook memory for secrets.
4. Persistence: Attackers may deploy webshells or reverse shells to maintain access to the development environment.

Exploitation Status: Confirmed Active Exploitation. Public proof-of-concept (PoC) code is available, lowering the barrier to entry for opportunistic attackers.

Detection & Response

Detecting this exploitation requires identifying when the Marimo application server spawns unexpected child processes or establishes abnormal network connections.

Sigma Rules

---
title: Potential Marimo CVE-2024-39338 Exploitation - Shell Spawn
id: 8a2b4c1d-5e6f-4a3b-8c9d-1e2f3a4b5c6d
status: experimental
description: Detects potential exploitation of CVE-2024-39338 by identifying the Marimo parent process spawning a shell (bash/sh), which is indicative of command execution.
references:
  - https://github.com/marimo-team/marimo/security/advisories
author: Security Arsenal
date: 2024/06/27
tags:
  - attack.execution
  - attack.t1059.004
logsource:
  category: process_creation
  product: linux
detection:
  selection:
    ParentImage|endswith:
      - '/marimo'
      - '/uvicorn' # Marimo often runs via uvicorn
    Image|endswith:
      - '/bash'
      - '/sh'
      - '/zsh'
      - '/dash'
  condition: selection
falsepositives:
  - Legitimate user running shell commands within the notebook (rare to spawn distinct shell process from parent in this manner)
level: high
---
title: Marimo Process Outbound Network Connection
id: 9b3c5d2e-6f7a-5b4c-9d0e-2f3a4b5c6d7e
status: experimental
description: Detects outbound network connections initiated by the Marimo process, potentially indicating C2 beaconing or data exfiltration post-exploitation.
references:
  - https://attack.mitre.org/techniques/T1071/
author: Security Arsenal
date: 2024/06/27
tags:
  - attack.exfiltration
  - attack.c2
  - attack.t1071.001
logsource:
  category: network_connection
  product: linux
detection:
  selection:
    Initiated: 'true'
    Image|endswith:
      - '/marimo'
      - '/uvicorn'
  condition: selection
falsepositives:
  - Notebook fetching external data packages/APIs (Verify destination IP)
level: medium

KQL (Microsoft Sentinel / Defender)

// Hunt for Marimo parent process spawning suspicious shells
DeviceProcessEvents
| where InitiatingProcessFileName has "marimo" or InitiatingProcessFileName has "uvicorn"
| where FileName in~ ("bash", "sh", "zsh", "dash", "python", "perl")
| project Timestamp, DeviceName, InitiatingProcessCommandLine, FileName, ProcessCommandLine, AccountName
| order by Timestamp desc

// Hunt for outbound network connections from Marimo process
DeviceNetworkEvents
| where InitiatingProcessFileName has "marimo" or InitiatingProcessFileName has "uvicorn"
| where ActionType == "ConnectionInitiated"
| project Timestamp, DeviceName, RemoteIP, RemotePort, RemoteUrl, InitiatingProcessCommandLine
| order by Timestamp desc

Velociraptor VQL

-- Hunt for processes spawned by marimo that look like reverse shells
SELECT Pid, Name, CommandLine, Exe, Username, CreateTime, PPid
FROM pslist()
WHERE Name =~ '^(bash|sh|zsh|dash|nc|python)'
  AND PPid IN (
    SELECT Pid FROM pslist() WHERE Name =~ 'marimo'
  )

Remediation Script (Bash)

#!/bin/bash
# Remediation script for CVE-2024-39338 (Marimo)
# Checks version and upgrades to 0.8.19 or later

echo "[*] Checking for Marimo installation..."

if ! command -v marimo &> /dev/null; then
    echo "[+] Marimo is not installed on this host in PATH."
    exit 0
fi

echo "[*] Detecting current Marimo version..."
CURRENT_VERSION=$(marimo version)
REQUIRED_VERSION="0.8.19"

echo "Current Version: $CURRENT_VERSION"
echo "Required Version: $REQUIRED_VERSION"

# Function to compare versions
version_gt() { test "$(printf '%s\n' "$@" | sort -V | head -n 1)" != "$1"; }

if version_gt "$REQUIRED_VERSION" "$CURRENT_VERSION"; then
    echo "[!] Vulnerable version detected ($CURRENT_VERSION). Initiating upgrade..."
    pip install -U marimo
    
    # Verify upgrade
    NEW_VERSION=$(marimo version)
    if version_gt "$REQUIRED_VERSION" "$NEW_VERSION"; then
        echo "[!] Upgrade failed. Please update manually via 'pip install -U marimo'"
    else
        echo "[+] Successfully upgraded to $NEW_VERSION"
    fi
else
    echo "[+] Marimo version $CURRENT_VERSION is safe."
fi

echo "[*] Checking for running Marimo processes..."
pgrep -f "marimo" && echo "[!] Warning: Marimo processes are currently running. Please restart the service to load the patched version."

Remediation & Hardening

1. Patch Immediately: Upgrade Marimo to version 0.8.19 or later. This can be done via pip install --upgrade marimo.
2. Restart Services: Simply upgrading the package is not enough if the process is still running in memory. Restart all Marimo notebook servers and any dependent services (like systemd services or Docker containers running Marimo).
3. Network Isolation: Marimo is a development tool and should rarely be exposed directly to the public internet. Ensure instances are behind a VPN, SSH tunnel, or Zero Trust network access solution. If public exposure is unavoidable, place it behind a Web Application Firewall (WAF) with strict rules.
4. Credential Rotation: If your instance was exposed to the internet before patching, assume that credentials stored in environment variables or notebook files may have been compromised. Rotate API keys and database passwords immediately.
5. Audit Logs: Review server logs (e.g., syslog, auth.log, or web server access logs) for suspicious requests around the /marimo endpoints or unexpected process launches prior to patching.

Official Advisory

For detailed release notes, see the official Marimo GitHub Security Advisory.

Related Resources

Security Arsenal Penetration Testing Services AlertMonitor Platform Book a SOC Assessment vulnerability-management Intel Hub