CVE-2011-3625 in Mplayer2
Summary
by MITRE
Stack-based buffer overflow in the sub_read_line_sami function in subreader.c in MPlayer, as used in SMPlayer 0.6.9, allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a long string in a SAMI subtitle file.
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Analysis
by VulDB Data Team • 05/01/2025
The vulnerability identified as CVE-2011-3625 represents a critical stack-based buffer overflow flaw within the MPlayer media player software ecosystem, specifically affecting the sub_read_line_sami function located in the subreader.c source file. This issue manifests when processing SAMI subtitle files, which are commonly used for displaying timed text overlays in multimedia presentations. The vulnerability exists in SMPlayer version 0.6.9, indicating that the flaw was present in a widely distributed media playback solution that many users rely upon for consuming various audio and video content formats. The buffer overflow occurs due to inadequate input validation and bounds checking within the subtitle parsing logic, creating an exploitable condition that can be triggered through maliciously crafted input data.
The technical exploitation of this vulnerability leverages the inherent properties of stack-based buffer overflows where insufficient bounds checking allows an attacker to write data beyond the allocated memory buffer boundaries. When a SAMI subtitle file contains an excessively long string, the sub_read_line_sami function fails to properly validate the input length before copying it into a fixed-size stack buffer. This condition creates a predictable memory corruption scenario where the overflow can overwrite adjacent stack variables, return addresses, and potentially execute arbitrary code if the attacker can control the overwritten memory contents. The vulnerability specifically targets the stack memory allocation pattern where local variables are stored in a contiguous memory block, making it susceptible to direct manipulation through buffer overflow techniques. This flaw aligns with CWE-121, which categorizes stack-based buffer overflow conditions as a fundamental memory safety issue.
The operational impact of CVE-2011-3625 extends beyond simple denial of service conditions to potentially enable remote code execution, making it a particularly dangerous vulnerability for users who frequently process multimedia content from untrusted sources. Attackers can craft malicious SAMI subtitle files that, when processed by vulnerable MPlayer installations, will trigger the buffer overflow condition and cause the application to crash or potentially execute malicious code with the privileges of the user running the media player. This scenario is particularly concerning in environments where users automatically load subtitle files from network sources or when the media player is used in automated processing scenarios. The vulnerability's remote exploitability means that attackers can deliver malicious content through web-based delivery mechanisms, email attachments, or shared network resources without requiring local system access. From an attack technique perspective, this vulnerability maps to ATT&CK technique T1203, which describes the exploitation of software vulnerabilities to gain code execution privileges.
Mitigation strategies for CVE-2011-3625 should focus on immediate software updates and input validation improvements. The most effective approach involves upgrading to patched versions of MPlayer and SMPlayer where the buffer overflow has been addressed through proper bounds checking and input validation mechanisms. Organizations should implement strict input validation policies for all multimedia file processing, including SAMI subtitle files, by implementing maximum string length limits and comprehensive parsing routines that prevent buffer overflows. Additionally, security-conscious administrators should consider implementing sandboxing techniques for media processing applications, limiting the potential impact of successful exploitation attempts. Network-level protections such as content filtering and web application firewalls can help prevent the delivery of malicious subtitle files to vulnerable systems. The vulnerability also underscores the importance of secure coding practices and regular security assessments, particularly for applications that process untrusted data from external sources. Implementing address space layout randomization and stack canaries can provide additional layers of protection against exploitation attempts, though these measures are secondary to proper input validation and software patching.