CVE-2011-2587 in VLC Media Player
Summary
by MITRE
Heap-based buffer overflow in the DemuxAudioSipr function in real.c in the RealMedia demuxer in VideoLAN VLC media player 1.1.x before 1.1.11 allows remote attackers to cause a denial of service (application crash) or possibly execute arbitrary code via a crafted Real Media file.
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Analysis
by VulDB Data Team • 11/15/2021
The vulnerability identified as CVE-2011-2587 represents a critical heap-based buffer overflow affecting the RealMedia demuxer component within VideoLAN VLC media player versions 1.1.x prior to 1.1.11. This flaw exists within the DemuxAudioSipr function in the real.c file, which processes RealMedia audio streams during media file demultiplexing operations. The vulnerability stems from insufficient input validation and bounds checking when handling specially crafted audio data within RealMedia container files, creating a condition where attacker-controlled data can overwrite adjacent heap memory regions beyond the allocated buffer boundaries.
The technical implementation of this vulnerability involves the improper handling of audio stream parameters during the demultiplexing process, specifically when processing SIPR (Smart Interleaved Prediction R) audio codecs used in RealMedia files. When VLC encounters a maliciously constructed RealMedia file, the DemuxAudioSipr function fails to properly validate the size parameters of audio frames before attempting to allocate or copy data into heap-allocated buffers. This allows an attacker to craft a file with oversized or malformed audio frame headers that trigger the buffer overflow condition, potentially leading to memory corruption that can be exploited to execute arbitrary code or cause application crashes.
The operational impact of CVE-2011-2587 extends beyond simple denial of service scenarios, as the heap-based nature of the vulnerability provides potential for remote code execution. An attacker could craft a malicious RealMedia file that, when opened by an unsuspecting user, would trigger the buffer overflow during playback, potentially allowing remote code execution on the victim's system. The vulnerability affects a widely used media player with extensive global deployment, making it particularly dangerous in environments where users frequently open multimedia content from untrusted sources. The exploitability of this vulnerability aligns with ATT&CK technique T1203 (Exploitation for Client Execution) and CWE-121 (Stack-based Buffer Overflow), though the heap-based nature specifically relates to CWE-122 (Heap-based Buffer Overflow) and CWE-787 (Out-of-bounds Write).
Mitigation strategies for CVE-2011-2587 require immediate patching of affected VLC installations to version 1.1.11 or later, which contains the necessary input validation fixes. Organizations should implement network-based restrictions to prevent access to potentially malicious RealMedia files through firewalls and content filtering systems. Additionally, user education regarding the risks of opening multimedia files from untrusted sources remains critical, as social engineering remains a primary attack vector for exploitation of such vulnerabilities. The fix implemented in the patched version addresses the root cause by introducing proper bounds checking and parameter validation before buffer allocation, preventing the overflow condition from occurring during audio stream processing. Security monitoring should include detection of suspicious file access patterns and potential exploitation attempts targeting media player components, particularly when users interact with multimedia content from external sources.