CVE-2023-46604 - CRITICAL - CWE-502 Deserialization of Untrusted Data

Executive Summary

A critical remote code execution (RCE) vulnerability, identified as CVE-2023-46604, has been discovered in Apache ActiveMQ. This vulnerability, with a CVSS score of 10, allows a remote attacker with network access to either a Java-based OpenWire broker or client to execute arbitrary shell commands. The attack leverages the manipulation of serialized class types in the OpenWire protocol, causing either the client or the broker to instantiate any class on the classpath. This means an attacker can essentially take control of the affected system. All users of Apache ActiveMQ are strongly urged to upgrade to versions 5.15.16, 5.16.7, 5.17.6, or 5.18.3 to mitigate this severe risk. Due to active exploitation, including its presence in the CISA KEV catalog, immediate action is crucial.

Vulnerability Snapshot

Technical Deep Dive

The root cause of CVE-2023-46604 lies in the insecure deserialization of untrusted data within the Java OpenWire protocol marshaller of Apache ActiveMQ. Deserialization is the process of converting a stream of bytes back into an object. When this process isn't carefully controlled, an attacker can manipulate the serialized data to inject malicious code.

In this particular case, the OpenWire protocol allows for the transmission of serialized Java objects between ActiveMQ brokers and clients. The vulnerability arises because the ActiveMQ broker or client doesn't properly validate the types of classes being deserialized. This allows an attacker to craft a malicious serialized object that, when deserialized, instantiates an arbitrary class on the classpath. This class can then be used to execute arbitrary shell commands on the server or client machine.

Here's a simplified illustration of how the attack works:

1. Attacker Crafts Malicious Payload: The attacker crafts a serialized Java object that, when deserialized, will instantiate a class that executes a command. This often involves using classes like org.springframework.context.support.FileSystemXmlApplicationContext or similar gadgets that can be manipulated to achieve code execution.

2. Payload Transmission: The attacker sends the malicious serialized object to the ActiveMQ broker or client using the OpenWire protocol.

3. Insecure Deserialization: The ActiveMQ broker or client receives the serialized object and attempts to deserialize it without proper validation.

4. Code Execution: The malicious object is instantiated, and its code is executed, allowing the attacker to run arbitrary shell commands.

// Example of a vulnerable deserialization process (simplified)
ObjectInputStream ois = new ObjectInputStream(inputStream);
Object obj = ois.readObject(); // Vulnerable line - no type validation

In the code snippet above, the readObject() method deserializes the object from the input stream. Without proper validation of the object's type, a malicious object can be instantiated, leading to code execution.

This vulnerability is particularly dangerous because it requires no authentication. An attacker only needs network access to the ActiveMQ broker or client to exploit it. The CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:H vector string confirms this:

• AV:N (Network): The vulnerability can be exploited over the network.
• AC:L (Low): The attack complexity is low, meaning it's relatively easy to exploit.
• PR:N (None): No privileges are required to exploit the vulnerability.
• UI:N (None): No user interaction is required.
• S:C (Changed): A successful exploit can affect components beyond the vulnerable component's security scope.
• C:L (Low): There is limited impact to confidentiality.
• I:H (High): There is a high impact to integrity.
• A:H (High): There is a high impact to availability.

Proof-of-Concept (POC) Insights

Public exploits are available for CVE-2023-46604, indicating that the vulnerability is well-understood and easily exploitable. A potential exploit is listed on Exploit-DB:

• Potential exploits may exist for CVE-2023-46604 (unknown)
  • Author: unknown
  • Link: https://www.exploit-db.com/search?cve=2023-46604

The existence of these POCs significantly increases the risk associated with this vulnerability, as attackers can readily use them to compromise vulnerable systems. The fact that it's in the CISA KEV catalog further underscores the active exploitation of this vulnerability.

Warning: POC code is intended for educational and research purposes only. Executing POC code can cause harm and may be illegal. Use extreme caution.

Threat Actor Activity

Based on 50 intelligence reports from AlienVault OTX, this vulnerability is being actively targeted by a variety of threat actors, including:

• APT Groups: Advanced Persistent Threat (APT) groups like APT29 are known to leverage this vulnerability in their campaigns. APT groups are typically state-sponsored and highly skilled.
• Nation-State Actors: Threat actors associated with North Korea are also exploiting this vulnerability.
• Cybercrime Groups: Groups like Onyx Sleet and Andariel are actively using this vulnerability for malicious purposes.

These threat actors are likely using CVE-2023-46604 to gain initial access to systems, escalate privileges, and deploy malware. Their targets likely include organizations in various sectors, including government, finance, and critical infrastructure.

Common MITRE ATT&CK techniques associated with this vulnerability include:

• T1190 - Exploit Public-Facing Application: Exploiting CVE-2023-46604 to gain initial access.
• T1566 - Phishing: Could be used as part of a phishing campaign to deliver the malicious payload.
• T1068 - Exploitation for Privilege Escalation: May be combined with other vulnerabilities to escalate privileges.
• T1059 - Command and Scripting Interpreter: Used to execute arbitrary commands after successful exploitation.

The active exploitation by diverse threat actors makes patching this vulnerability a top priority.

Impact Assessment

The exploitation of CVE-2023-46604 can have severe consequences:

• Confidentiality: An attacker can gain access to sensitive data stored on the affected system.
• Integrity: An attacker can modify or delete data, potentially disrupting business operations.
• Availability: An attacker can cause a denial-of-service (DoS) condition, making the system unavailable to legitimate users.

The impact is further amplified by the S:C scope change in the CVSS vector, meaning that a successful exploit can affect components beyond the immediate ActiveMQ broker or client. This could lead to a compromise of the entire network.

For organizations using cloud service providers, including AWS, the impact can be significant. A compromised ActiveMQ broker could allow an attacker to access other cloud resources, such as databases, storage buckets, and virtual machines. This could lead to data breaches, service disruptions, and compliance violations.

Cloud Service Provider Implications

While there's no direct AWS impact identified, the moderate relevance to cloud service providers means careful consideration is needed, especially for PaaS offerings:

• AWS-Hosted Applications: Applications using Apache ActiveMQ on EC2 instances or within containerized environments (e.g., EKS, ECS) are vulnerable if running affected versions.
• Customer-Managed Components: The vulnerability primarily resides in customer-managed ActiveMQ instances, not AWS-managed services. Customers are responsible for patching their ActiveMQ deployments.
• Blast Radius: In multi-tenant environments, a compromised ActiveMQ instance could potentially lead to lateral movement and compromise of other tenants if proper isolation is not in place.
• Data Residency/Compliance: Data stored or processed by compromised ActiveMQ instances might be subject to data residency or compliance regulations, leading to legal and financial repercussions.
• Security Control Bypass: Successful exploitation could bypass existing security controls, such as firewalls and intrusion detection systems.

Mitigation and Remediation

The primary mitigation for CVE-2023-46604 is to update to the latest version of Apache ActiveMQ:

• Upgrade both brokers and clients to version 5.15.16, 5.16.7, 5.17.6, or 5.18.3.

Due to active exploitation and its presence in the CISA KEV catalog, patching should be performed as soon as possible.

In addition to patching, consider the following workarounds:

• Network Segmentation: Isolate ActiveMQ brokers in a separate network segment to limit the potential impact of a compromise.
• Access Control Lists (ACLs): Implement strict ACLs to restrict access to ActiveMQ brokers to only authorized users and systems.
• Input Validation: Implement input validation to prevent the deserialization of untrusted data. However, this workaround may not be effective against all attack vectors.
• Monitor for Suspicious Activity: Monitor ActiveMQ logs for suspicious activity, such as attempts to deserialize unexpected classes.

For AWS environments, consider the following cloud-specific mitigations:

• AWS Security Groups: Use Security Groups to restrict network access to ActiveMQ brokers.
• AWS WAF: Implement WAF rules to filter malicious traffic to ActiveMQ brokers.
• AWS CloudTrail: Monitor CloudTrail logs for suspicious activity related to ActiveMQ.
• AWS Inspector: Use Inspector to identify vulnerable ActiveMQ instances.

References

• https://activemq.apache.org/security-advisories.data/CVE-2023-46604-announcement.txt
• https://www.openwall.com/lists/oss-security/2023/10/27/5
• https://security.netapp.com/advisory/ntap-20231110-0010/
• https://packetstormsecurity.com/files/175676/Apache-ActiveMQ-Unauthenticated-Remote-Code-Execution.html
• https://lists.debian.org/debian-lts-announce/2023/11/msg00013.html
• http://seclists.org/fulldisclosure/2024/Apr/18

Conclusion

CVE-2023-46604 is a critical remote code execution vulnerability in Apache ActiveMQ that poses a significant risk to organizations. The active exploitation of this vulnerability by diverse threat actors, coupled with the availability of public exploits, makes it imperative to patch affected systems immediately. Organizations using cloud service providers, especially those with workloads on AWS PaaS offerings, should prioritize patching and implement appropriate cloud-specific mitigations. Stay informed, stay vigilant, and prioritize security.