CVE-2007-1804 in PulseAudio
Summary
by MITRE
PulseAudio 0.9.5 allows remote attackers to cause a denial of service (daemon crash) via (1) a PA_PSTREAM_DESCRIPTOR_LENGTH value of FRAME_SIZE_MAX_ALLOW sent on TCP port 9875, which triggers a p->export assertion failure in do_read; (2) a PA_PSTREAM_DESCRIPTOR_LENGTH value of 0 sent on TCP port 9875, which triggers a length assertion failure in pa_memblock_new; or (3) an empty packet on UDP port 9875, which triggers a t assertion failure in pa_sdp_parse; and allows remote authenticated users to cause a denial of service (daemon crash) via a crafted packet on TCP port 9875 that (4) triggers a maxlength assertion failure in pa_memblockq_new, (5) triggers a size assertion failure in pa_xmalloc, or (6) plays a certain sound file.
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Analysis
by VulDB Data Team • 12/28/2024
The vulnerability described in CVE-2007-1804 affects PulseAudio version 0.9.5 and represents a series of denial of service conditions that can be exploited remotely through network connections to the audio daemon. This issue demonstrates a classic example of input validation failures that can lead to daemon crashes and service disruption. The vulnerability exists within the network protocol handling mechanisms of PulseAudio's server implementation, specifically targeting the daemon's ability to process incoming data streams through TCP and UDP connections on designated ports.
The technical flaw manifests through multiple distinct attack vectors that exploit different assertion failures within the PulseAudio codebase. The first vector involves sending a PA_PSTREAM_DESCRIPTOR_LENGTH value of FRAME_SIZE_MAX_ALLOW to TCP port 9875, which triggers a p->export assertion failure in the do_read function, causing the daemon to crash. The second vector uses a PA_PSTREAM_DESCRIPTOR_LENGTH value of zero, which results in a length assertion failure within pa_memblock_new, another critical daemon crash scenario. Additionally, attackers can send empty packets to UDP port 9875, triggering a t assertion failure in pa_sdp_parse function. These multiple attack vectors demonstrate the comprehensive nature of the vulnerability across different protocol handling components.
The operational impact of this vulnerability extends beyond simple service disruption to potentially enable more sophisticated attacks. Remote authenticated users can exploit additional vectors including crafted packets that trigger maxlength assertion failures in pa_memblockq_new, size assertion failures in pa_xmalloc, or even playing specific sound files to cause daemon crashes. This multi-layered approach to exploitation makes the vulnerability particularly dangerous as it can be triggered through various means and potentially from different privilege levels. The vulnerability affects systems running PulseAudio 0.9.5 and demonstrates a fundamental lack of proper input sanitization and boundary checking in the audio streaming protocol implementation.
Security practitioners should recognize this vulnerability as a classic example of buffer overflow and assertion failure exploitation patterns that align with CWE-129 and CWE-682 categories. The attack vectors correspond to various MITRE ATT&CK techniques including T1499 for network denial of service and T1059 for command and control communications. The vulnerability specifically targets the daemon's memory management and stream processing functions, making it particularly effective for disrupting audio services in desktop and server environments. Organizations should immediately implement mitigations including firewall rules blocking access to ports 9875 for TCP and UDP protocols, updating to patched versions of PulseAudio, and implementing network segmentation to limit exposure. The vulnerability also highlights the importance of proper assertion handling and input validation in network services, as these failures can create multiple paths for service disruption attacks that can be exploited remotely without requiring special privileges beyond basic network access.
The broader implications of this vulnerability extend to system reliability and availability in environments where audio services are critical. Systems relying on PulseAudio for audio processing, including desktop environments, multimedia applications, and server-based audio services, could experience complete service disruption when exploited. The vulnerability demonstrates how seemingly minor protocol handling issues can lead to complete daemon crashes, emphasizing the need for comprehensive testing of network protocol implementations and proper error handling mechanisms. This vulnerability serves as a reminder of the critical importance of robust input validation and assertion checking in network services, particularly those that handle multimedia streams and audio data processing.