CVE-2018-6360 in mpv
Summary
by MITRE
mpv through 0.28.0 allows remote attackers to execute arbitrary code via a crafted web site, because it reads HTML documents containing VIDEO elements, and accepts arbitrary URLs in a src attribute without a protocol whitelist in player/lua/ytdl_hook.lua. For example, an av://lavfi:ladspa=file= URL signifies that the product should call dlopen on a shared object file located at an arbitrary local pathname. The issue exists because the product does not consider that youtube-dl can provide a potentially unsafe URL.
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Analysis
by VulDB Data Team • 02/02/2023
The vulnerability identified as CVE-2018-6360 represents a critical remote code execution flaw in the mpv media player version 0.28.0 and earlier. This security weakness stems from insufficient input validation within the player's lua scripting environment, specifically in the ytdl_hook.lua file that handles youtube-dl integration. The vulnerability manifests when mpv processes HTML documents containing VIDEO elements with src attributes that reference arbitrary URLs without proper protocol filtering. This design flaw allows attackers to craft malicious websites that, when opened in mpv, can execute arbitrary code on the victim's system through the player's handling of multimedia content.
The technical exploitation of this vulnerability leverages the player's trust in youtube-dl's URL resolution capabilities without adequate validation of the resulting URLs. When a VIDEO element references a URL such as av://lavfi:ladspa=file=, the mpv player interprets this as a directive to load a shared object file using dlopen, effectively bypassing normal file access restrictions. This behavior occurs because the player's lua hook does not implement a protocol whitelist, allowing any URL scheme to be processed without verification. The vulnerability directly maps to CWE-20, "Improper Input Validation," and specifically demonstrates the dangers of trusting external content providers without proper sanitization mechanisms. The attack vector is particularly insidious because it can be delivered through standard web browsing activities, making it accessible to attackers with minimal technical expertise.
The operational impact of this vulnerability extends beyond simple code execution to encompass complete system compromise. An attacker could craft malicious web pages that, when viewed in mpv, would download and execute arbitrary shared libraries or executables from remote servers, potentially leading to full system control. The vulnerability affects users who browse the internet with mpv as their default media player, making it particularly dangerous in environments where users frequently access untrusted websites. This flaw creates a persistent threat vector that could be exploited through various attack surfaces including phishing campaigns, malicious advertisements, or compromised websites that embed malicious video content.
Mitigation strategies for CVE-2018-6360 should focus on implementing protocol whitelisting within the player's lua scripting environment to prevent execution of unsafe URL schemes. Users should update to mpv version 0.28.1 or later, which includes patches addressing this vulnerability. Security administrators should consider implementing network-level restrictions that prevent access to potentially malicious URL schemes, particularly those related to local file access protocols. The fix implemented by the mpv development team involved adding proper URL validation to the ytdl_hook.lua script, ensuring that only whitelisted protocols are accepted for processing. This approach aligns with ATT&CK technique T1059.007, "Command and Scripting Interpreter: Lua," by preventing unauthorized script execution through malicious URL handling. Organizations should also implement application whitelisting policies that restrict mpv's ability to execute arbitrary code through external content sources, reducing the attack surface and providing defense in depth against similar vulnerabilities.