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April 19, 2025
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How to Fix CVE-2025-32433: Critical Remote Code Execution Vulnerability in Erlang/OTP SSH Server?
This article provides a comprehensive guide for security professionals to remediate CVE-2025-32433, a critical remote code execution (RCE) vulnerability in the Erlang/OTP SSH server. This flaw allows unauthenticated attackers to execute arbitrary code remotely, potentially leading to complete system compromise. We will cover the vulnerability's details, its impact, affected products, and step-by-step instructions on how to fix it. This information is intended to help security professionals working in DevSecOps, application security, product security, vulnerability management, penetration testing, and security operations to effectively protect their systems.
A Short Introduction to Erlang/OTP
Erlang/OTP is a general-purpose programming language and a set of open-source libraries and design principles, primarily used for building concurrent, distributed, and fault-tolerant systems. Its OTP (Open Telecom Platform) framework provides a robust set of tools and libraries for developing scalable and reliable applications, including an SSH server implementation. Erlang/OTP is popular in telecommunications, banking, e-commerce, and other industries that require high availability and reliability. The SSH server component allows for secure remote access and management of Erlang-based systems.
Summary of CVE-2025-32433
CVE ID: CVE-2025-32433
Description: Unauthenticated remote code execution vulnerability in Erlang/OTP SSH server due to a flaw in SSH protocol message handling.
CVSS Score: 10.0 (Critical)
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CVE-2025-32433 describes a critical security vulnerability affecting the Erlang/OTP SSH server. The vulnerability allows an unauthenticated attacker to remotely execute arbitrary code on a vulnerable system. This flaw is rooted in the improper handling of SSH protocol messages. By sending specially crafted messages to the SSH server, an attacker can bypass authentication mechanisms and execute commands with the privileges of the Erlang/OTP system user. The CVSS score of 10.0 reflects the severity of this vulnerability, as successful exploitation can lead to complete system compromise without requiring any user interaction. The attack complexity is low, making it easier for attackers to exploit.
Impact of CVE-2025-32433
The impact of CVE-2025-32433 is severe due to the potential for unauthenticated remote code execution. An attacker who successfully exploits this vulnerability can gain complete control over the affected Erlang/OTP SSH server. This can lead to a number of critical consequences, including:
Remote Command Execution: Attackers can execute arbitrary commands on the targeted system, allowing them to install malware, modify system configurations, or steal sensitive data.
System Compromise: Full control over the system allows attackers to compromise the entire Erlang/OTP environment, potentially disrupting critical applications and services.
Data Exfiltration: Attackers can access and exfiltrate sensitive data stored on the system, leading to data breaches and compliance violations.
Lateral Movement: Compromised systems can be used as a launching point to attack other systems within the network, escalating the impact of the breach.
Denial of Service: Attackers can disrupt or disable the SSH server, preventing legitimate users from accessing the system.
Given the potential for complete system compromise and the ease of exploitation, organizations using affected versions of Erlang/OTP must take immediate action to address this vulnerability.
Products Affected by CVE-2025-32433
The following Erlang/OTP versions are affected by the CVE-2025-32433 vulnerability:
|
Product
|
Affected Versions
|
|---|---|
|
Erlang/OTP
|
Prior to OTP-27.3.3
|
|
Erlang/OTP
|
Prior to OTP-26.2.5.11
|
|
Erlang/OTP
|
Prior to OTP-25.3.2.20
|
Note: All versions of Erlang/OTP prior to the patched versions listed above are considered vulnerable.
How to Check Your Product is Vulnerable?
To determine if your Erlang/OTP installation is vulnerable, follow these steps:
Check the Erlang/OTP Version: Connect to the system where Erlang/OTP is installed. Open an Erlang shell by typing
erlin the command line.Verify the Version: Inside the Erlang shell, the version number will be displayed when the shell starts. Alternatively, you can use the command
erlang:system_info(otp_release).to display the OTP release version.Compare with Affected Versions: Compare the reported version with the affected versions listed in the table above. If your version is older than OTP-27.3.3, OTP-26.2.5.11, or OTP-25.3.2.20, your system is vulnerable.
SSH banner analysis: Connect to your Erlang/OTP SSH server using an SSH client. Examine the SSH banner displayed upon connection, which may reveal the Erlang/OTP version.
Network traffic analysis: Monitor network traffic for suspicious patterns or malformed SSH packets that could indicate exploitation attempts.
How to Fix the Vulnerabilities?
The primary remediation strategy for CVE-2025-32433 is to update Erlang/OTP to a patched version. Follow these steps to mitigate the vulnerability:
Upgrade Erlang/OTP: Upgrade to one of the following patched versions:
OTP-27.3.3
OTP-26.2.5.11
OTP-25.3.2.20
Follow the Official Upgrade Guide: Refer to the official Erlang/OTP documentation for detailed instructions on how to upgrade your installation. Ensure you back up your system before performing the upgrade.
Verify the Patch: After the upgrade, verify that the Erlang/OTP version is one of the patched versions. Restart the Erlang/OTP system to ensure the new version is running.
Monitor for Suspicious Activity: Continuously monitor your systems for any signs of unauthorized access or suspicious activity.
Workarounds:
If immediate patching is not possible, consider these temporary workarounds:
Disable SSH Server: Temporarily disable the Erlang/OTP SSH server if it is not critical for operations. This will prevent attackers from exploiting the vulnerability.
Implement Strict Firewall Rules: Implement strict network firewall rules to restrict SSH access to only trusted IP addresses or networks. This will limit the attack surface and reduce the risk of exploitation.
Monitor Official Channels: Stay informed about updates by continuously monitoring Erlang/OTP's official communication channels.
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Arun KL
Arun KL is a cybersecurity professional with 15+ years of experience in IT infrastructure, cloud security, vulnerability management, Penetration Testing, security operations, and incident response. He is adept at designing and implementing robust security solutions to safeguard systems and data. Arun holds multiple industry certifications including CCNA, CCNA Security, RHCE, CEH, and AWS Security.
- April 19, 2025
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- April 19, 2025
