CVE-2014-1916 in Mumble
Summary
by MITRE
The (1) opus_packet_get_nb_frames and (2) opus_packet_get_samples_per_frame functions in the client in MumbleKit before commit fd190328a9b24d37382b269a5674b0c0c7a7e36d and Mumble for iOS 1.1 through 1.2.2 do not properly check the return value of the copyDataBlock method, which allow remote attackers to cause a denial of service (NULL pointer dereference and crash) via a crafted length prefix value in an Opus voice packet.
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Analysis
by VulDB Data Team • 03/06/2019
The vulnerability identified as CVE-2014-1916 resides within the MumbleKit client library and Mumble for iOS applications, specifically affecting versions prior to commit fd190328a9b24d37382b269a5674b0c0c7a7e36d and iOS versions 1.1 through 1.2.2. This issue manifests in two critical functions namely opus_packet_get_nb_frames and opus_packet_get_samples_per_frame which are responsible for processing Opus voice packets within the communication framework. The flaw stems from inadequate validation of return values from the copyDataBlock method, creating a condition where maliciously crafted voice packets can trigger unexpected behavior in the application's packet processing pipeline. The vulnerability operates at the intersection of input validation and memory management, where the failure to properly verify the outcome of data copying operations creates a path for exploitation.
The technical implementation of this vulnerability involves the manipulation of length prefix values within Opus voice packets, which are fundamental components of the audio streaming protocol used by Mumble. When these functions process packets containing crafted length prefixes, the copyDataBlock method fails to return proper validation results, allowing the application to proceed with null or invalid data references. This particular flaw represents a classic null pointer dereference scenario that falls under the CWE-476 category of NULL Pointer Dereference, where the application attempts to access memory locations that have not been properly initialized or validated. The exploitation mechanism is straightforward yet effective, requiring only a specially crafted packet to trigger the vulnerability, making it particularly dangerous in networked environments where audio streams are continuously processed.
The operational impact of this vulnerability extends beyond simple denial of service, as it can be leveraged to cause complete application crashes and potentially disrupt communication services within Mumble networks. When a remote attacker sends a malformed Opus packet with manipulated length prefixes, the affected client applications will crash upon attempting to process these packets, resulting in service disruption for legitimate users. This vulnerability particularly affects real-time voice communication systems where continuous packet processing is essential, as a single malicious packet can terminate the entire client application. The attack vector is remote and requires no authentication, making it accessible to any networked user capable of sending packets to the target system, which aligns with ATT&CK technique T1203 for legitimate user execution and T1499 for network denial of service.
Mitigation strategies for CVE-2014-1916 should focus on implementing proper input validation and error handling within the affected functions. The most effective solution involves ensuring that all return values from copyDataBlock method are properly checked before proceeding with further processing, particularly verifying that the copied data is valid and non-null before attempting to access it. This approach aligns with secure coding practices recommended in the OWASP Secure Coding Guidelines and addresses the underlying CWE-476 vulnerability by preventing null pointer dereference conditions. Additionally, implementing bounds checking on length prefix values and employing defensive programming techniques such as input sanitization can significantly reduce the attack surface. Organizations should also consider deploying network monitoring solutions to detect and block malformed Opus packets, while ensuring that all affected systems are updated to patched versions that properly handle these edge cases in packet processing. The fix typically involves adding explicit validation checks that ensure the copyDataBlock method returns valid data before proceeding with the frame and sample calculations, thereby preventing the NULL pointer dereference that leads to application crashes.