CVE-2017-5878 in Media Server
Summary
by MITRE
The AMF unmarshallers in Red5 Media Server before 1.0.8 do not restrict the classes for which it performs deserialization, which allows remote attackers to execute arbitrary code via crafted serialized Java data.
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Analysis
by VulDB Data Team • 10/14/2019
The vulnerability identified as CVE-2017-5878 represents a critical deserialization flaw within the Red5 Media Server platform, specifically affecting versions prior to 1.0.8. This issue resides in the Action Message Format (AMF) unmarshallers that handle data serialization and deserialization processes. The flaw stems from insufficient class validation mechanisms that permit deserialization of arbitrary Java objects without proper restrictions on the target classes. Attackers can exploit this weakness by crafting malicious serialized Java data that, when processed by the vulnerable server, triggers unintended code execution. The vulnerability operates at the core of the server's data handling infrastructure, where AMF protocol is used for efficient communication between client and server components.
The technical exploitation of this vulnerability follows a classic deserialization attack pattern that aligns with CWE-502, which specifically addresses deserialization of untrusted data. When the Red5 server receives crafted AMF data containing serialized Java objects, the unmarshaller processes these objects without validating whether the target classes are safe or authorized for execution. This lack of input sanitization creates an attack surface where malicious actors can inject payload code that executes with the privileges of the Red5 server process. The vulnerability is particularly dangerous because it allows for remote code execution without requiring authentication, making it an attractive target for automated exploitation tools. The attack chain typically involves crafting serialized objects that, when deserialized, trigger malicious behavior through Java's reflection mechanisms or by leveraging existing classes within the application's classpath.
The operational impact of CVE-2017-5878 extends beyond simple code execution to encompass complete system compromise and potential lateral movement within network environments. Since Red5 Media Server is commonly deployed for streaming media services and real-time communication applications, exploitation could lead to unauthorized access to sensitive media content, disruption of streaming services, or use as a foothold for further attacks. The vulnerability's remote exploitability means that attackers can target systems from anywhere on the internet without requiring physical access or prior authentication. Organizations utilizing Red5 for media streaming, web conferencing, or other real-time applications face significant risk, as this vulnerability can be exploited through various attack vectors including web interfaces, API endpoints, or direct socket connections. The attack surface is further expanded due to the widespread deployment of Red5 in enterprise environments for multimedia applications.
Mitigation strategies for CVE-2017-5878 should prioritize immediate patching of affected Red5 Media Server installations to version 1.0.8 or later, which includes proper class restriction mechanisms for deserialization operations. Organizations should implement network segmentation to limit access to Red5 servers and restrict external exposure where possible. Additional protective measures include deploying application firewalls, implementing strict input validation for all AMF data, and monitoring for suspicious deserialization patterns in system logs. Security teams should also consider implementing runtime application self-protection measures and regularly auditing the classpath for potentially dangerous deserialization targets. The vulnerability demonstrates the importance of following secure coding practices as outlined in OWASP Top Ten and MITRE ATT&CK framework, particularly focusing on preventing deserialization attacks and maintaining proper input validation controls. Organizations should conduct comprehensive security assessments of their Red5 deployments and ensure that all network services utilizing AMF protocols have proper access controls and monitoring in place to detect potential exploitation attempts.