Summary
A Java deserialization flaw in the Tribes-based clustering component of Apache Axis2/Java allows arbitrary code execution when crafted serialized objects are processed on the cluster channel.
When Tribes clustering is enabled on Apache Tomcat and the clustering port is reachable, an unauthenticated remote attacker can send malicious objects that are deserialized by Axis2ChannelListener, leading to full compromise of the affected application node.
A Java deserialization flaw in the Tribes-based clustering component of Apache Axis2/Java allows arbitrary code execution when crafted serialized objects are processed on the cluster channel.
When Tribes clustering is enabled on Apache Tomcat and the clustering port is reachable, an unauthenticated remote attacker can send malicious objects that are deserialized by Axis2ChannelListener, leading to full compromise of the affected application node.
Affected context
This vulnerability appears in Apache Axis2/Java deployments that:
- Are running on Apache Tomcat
- Have Tribes-based clustering explicitly enabled (disabled by default)
- Expose the clustering communication port to a reachable network segment
In this context, Axis2's clustering listener (Axis2ChannelListener#messageReceived) processes serialized Java objects arriving over the cluster channel, creating an attack surface whenever the port is accessible to untrusted parties.
This vulnerability appears in Apache Axis2/Java deployments that:
- Are running on Apache Tomcat
- Have Tribes-based clustering explicitly enabled (disabled by default)
- Expose the clustering communication port to a reachable network segment
In this context, Axis2's clustering listener (Axis2ChannelListener#messageReceived) processes serialized Java objects arriving over the cluster channel, creating an attack surface whenever the port is accessible to untrusted parties.
Exploit preconditions
- Attack surface: Network-accessible Tribes clustering port on the Tomcat host
- Required access: Unauthenticated network access to the Axis2 cluster communication channel
- Trigger point: Delivery of a specially crafted serialized Java object to the cluster port, causing deserialization in
Axis2ChannelListener#messageReceived - Why exploitation is possible: The listener accepts and deserializes untrusted Java objects without applying type whitelisting, integrity checks, or sandboxing, allowing attacker-controlled object graphs to execute arbitrary code via gadget chains
- Attack surface: Network-accessible Tribes clustering port on the Tomcat host
- Required access: Unauthenticated network access to the Axis2 cluster communication channel
- Trigger point: Delivery of a specially crafted serialized Java object to the cluster port, causing deserialization in
Axis2ChannelListener#messageReceived - Why exploitation is possible: The listener accepts and deserializes untrusted Java objects without applying type whitelisting, integrity checks, or sandboxing, allowing attacker-controlled object graphs to execute arbitrary code via gadget chains
Why this happens
The underlying bug belongs to the unsafe deserialization class (CWE-502), where untrusted serialized data is treated as trusted input and passed directly to Java's object deserialization mechanisms.
In Axis2's Tribes clustering implementation, received cluster messages are deserialized and reconstituted as Java objects without enforcing strict type constraints or validating their origin, enabling attackers to supply gadget chains that invoke dangerous methods during or after deserialization.
Abstractly, this pattern occurs whenever a remote endpoint accepts serialized objects from outside its trust boundary and reconstructs them with full application privileges, effectively converting data into executable behavior.
The underlying bug belongs to the unsafe deserialization class (CWE-502), where untrusted serialized data is treated as trusted input and passed directly to Java's object deserialization mechanisms.
In Axis2's Tribes clustering implementation, received cluster messages are deserialized and reconstituted as Java objects without enforcing strict type constraints or validating their origin, enabling attackers to supply gadget chains that invoke dangerous methods during or after deserialization.
Abstractly, this pattern occurs whenever a remote endpoint accepts serialized objects from outside its trust boundary and reconstructs them with full application privileges, effectively converting data into executable behavior.
Potential impact
- Remote execution of arbitrary code on the Axis2/Java application server
- Full compromise of the affected Tomcat process and its hosted web services
- Lateral movement within the cluster or broader infrastructure
- Access to sensitive data processed or stored by Axis2 services
- Service disruption, including denial-of-service or deployment of ransomware
- Remote execution of arbitrary code on the Axis2/Java application server
- Full compromise of the affected Tomcat process and its hosted web services
- Lateral movement within the cluster or broader infrastructure
- Access to sensitive data processed or stored by Axis2 services
- Service disruption, including denial-of-service or deployment of ransomware
General mitigation guidance
Effective mitigation focuses on eliminating unsafe deserialization pathways and reducing trust in remote cluster traffic.
Common defensive patterns include:
- Avoiding generic Java object deserialization for network messages; prefer structured formats (JSON, XML, protobuf) with explicit schema validation
- Applying strict type whitelisting and serialization filters when deserialization cannot be removed, ensuring only known-safe classes are reconstructed
- Constraining or disabling clustering features that accept serialized objects from untrusted networks, and isolating such channels behind internal network boundaries
- Running the application under least-privilege accounts so that a compromise has limited system-wide impact
- Designing inter-node communication protocols that treat all incoming data as untrusted and validate it before use
Effective mitigation focuses on eliminating unsafe deserialization pathways and reducing trust in remote cluster traffic.
Common defensive patterns include:
- Avoiding generic Java object deserialization for network messages; prefer structured formats (JSON, XML, protobuf) with explicit schema validation
- Applying strict type whitelisting and serialization filters when deserialization cannot be removed, ensuring only known-safe classes are reconstructed
- Constraining or disabling clustering features that accept serialized objects from untrusted networks, and isolating such channels behind internal network boundaries
- Running the application under least-privilege accounts so that a compromise has limited system-wide impact
- Designing inter-node communication protocols that treat all incoming data as untrusted and validate it before use
How teams detect issues like this
High-level detection typically combines code-centric and operational views:
- Static analysis rules that flag usage of
ObjectInputStreamand similar deserialization APIs on network or remote inputs, especially in clustering or messaging components - Code review focusing on classes that implement cluster listeners, message handlers, or custom serialization logic, looking for absent type checks and trust boundaries
- Security policies in CI/CD that require serialization filters or safe data formats for any newly introduced remote communication endpoints
- Runtime monitoring and logging of unusual cluster traffic patterns, unexpected object types, or deserialization errors, which can signal probing or exploitation attempts
- Use of automated security testing tools that attempt to inject crafted serialized payloads into identified deserialization sinks during QA or pre-production testing
High-level detection typically combines code-centric and operational views:
- Static analysis rules that flag usage of
ObjectInputStreamand similar deserialization APIs on network or remote inputs, especially in clustering or messaging components - Code review focusing on classes that implement cluster listeners, message handlers, or custom serialization logic, looking for absent type checks and trust boundaries
- Security policies in CI/CD that require serialization filters or safe data formats for any newly introduced remote communication endpoints
- Runtime monitoring and logging of unusual cluster traffic patterns, unexpected object types, or deserialization errors, which can signal probing or exploitation attempts
- Use of automated security testing tools that attempt to inject crafted serialized payloads into identified deserialization sinks during QA or pre-production testing
Sources
| Source | Link |
|---|---|
| github. | github.com/ |
| lists. | lists.apache.org/ |
| openwall. | openwall.com/ |
