HTML5 Group 3: Dongyang Zhang, Wei Liu, Weizhou He, Yutong Wei, Yuxin Zhu.

Contents Setup 12 Abusing Sockets, XHR 3 About DOM

Setup Domain: attacker.com IP: OS: Windows server 2012 Server: IIS 8.0 Domain: victimserver.com IP: OS: Windows server 2012 Server: IIS 8.0 Language:.Net C# Ip: OS: Windows XP Browser: Chrome 1

Abusing sockets, XHR SOP Vulnerabilities!! Script, IMG, Iframe bypasses 1 2 DNS Rebinding 3 PostMessage Mechanism 2

Script, IMG, Iframe bypasses

DNS Rebinding DNS rebinding is an exploit in which the attacker uses Javascript in a malicious Web page to gain control of the victim’s router. 4

DNS Rebinding visit Malicious Website Attacker’s DNS server bind attacker.com to attacker’s IP address (short TTL). 5

DNS Rebinding Malicious script uses XMLHttpRequest Attacker rebinds attacker.com to target’s IP address. In fact 6

DNS Rebinding 7

SOP Violation! 8

DNS Rebinding 9

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DNS Rebinding Browser’s DNS cache DNS request flooding 11

DNS Rebinding Firewall Circumvention: -Access Machine behind firewalls -Interact with a number of internal services besides HTTP(direct socket access) 12

DNS Rebinding IP Hijacking: -Access publicly available servers from client’s IP -Take advantage of the target’s implicit or explicit trust in client’s I address 13

DOM DOM(Document Object Model) 14

DOM We all know that: ① Reflected XSS ② Stored XSS both purely inside client-side code 15

DOM The third kind of XSS: DOM Based XSS which is not depended on the malicious data send to the service at the first time 16

DOM The API may vulnerable in DOM based XSS 17

DOM 1). document.location 2). document.URL 3). document.URLUnencoded 4). document.referrer 5). window.location These API can visit DOM data through a designed URL, but this kind of jumped-out window is not really harmful, attacker has no idea if users never click on the URL. 18

DOM 1). document.write() 2). document.writeln() 3). document.boby.innerHtml 4). eval() 5). window.execScript() 6). window.setInterval() 7). window.setTimeout() These API are mostly used in form hijacking, inject a part of XSS code while users submit the forms. This is more dangerous, most of them are used in stealing cookie. 19

EXAMPLE: document.boby.innerHtml While running this code, xxx will take the value of “yyyyyy” “yyyyyy” can be replaced by something else like “ ” or Unicode like “\u003cimg src=1\u003e”. xxx document.getElementById("a").innerHTML="yyyyyy"; 20

EXAMPLE: document.boby.innerHtml Real example: qq.com (most of you should know this right? ☺ ) 21

EXAMPLE: document.boby.innerHtml URL: bin/search?libid=1&keyvalue=aaaaaaa&attr=133&stype=2&tname=star_s econd.shtml (there was some vulnerabilities, but there isn’t now, I think) search_by job1: aaaaaaa if("aaaaaaa"=="") document.getElementById("titleshow").innerHTML="search_by_place: all_stars"; if("job1"=="job1") document.getElementById("titleshow").innerHTML="search_by_job: aaaaaaa"; if("job1"=="job2") document.getElementById("titleshow").innerHTML="search_by_job: aaaaaaa"; if("job1"=="job3") document.getElementById("titleshow").innerHTML="search_by_job: aaaaaaa"; 22

EXAMPLE: document.boby.innerHtml We know that “ ”would not be recognized, but “/”can be recongnized, So perhaps we should try Unicode! We see that if(“job1”==“job1”) is executed, so we focus on this two lines of code. search_by job1: aaaaaaa if("aaaaaaa"=="") document.getElementById("titleshow").innerHTML="search_by_place: all_stars"; if("job1"=="job1") document.getElementById("titleshow").innerHTML="search_by_job: aaaaaaa"; if("job1"=="job2") document.getElementById("titleshow").innerHTML="search_by_job: aaaaaaa"; if("job1"=="job3") document.getElementById("titleshow").innerHTML="search_by_job: aaaaaaa"; 23

EXAMPLE: document.boby.innerHtml As we know from above, we can change “aaaaaaa” into “\u003cimg src=1 onerror=alert(1)\u003e ” search_by job1: aaaaaaa if("aaaaaaa"=="") document.getElementById("titleshow").innerHTML="search_by_place: all_stars"; if("job1"=="job1") document.getElementById("titleshow").innerHTML="search_by_job: aaaaaaa"; if("job1"=="job2") document.getElementById("titleshow").innerHTML="search_by_job: aaaaaaa"; if("job1"=="job3") document.getElementById("titleshow").innerHTML="search_by_job: aaaaaaa"; 24

EXAMPLE: document.boby.innerHtml This is an example we learn when we try to get a better understand on DOM based XSS, we didn’t actually attack this website, and this vulnerability has been reported! 25

DOM 1). document.location 2). document.URL 3). document.open() 4). window.location.href 5). window.navigate() 6). window.open These API are mostly used in redirection attack. The perniciousness can be big or small, but this kind of perniciousness are often eaily ignored by people. 26

DOM Differences between Standard XSS and DOM based XSS 27

DOM 28

DOM How to find DOM based XSS 29

DOM 1). Using byte level taint tracking in chromium - precise source information for every character - patched sinks (for example document. write) 2). Chrome extension to crawl given set of web site - also act as interface between taint engine and backend 3). And an exploit generator - using precise taint information - and javascript and HTML syntax rules - to generate exploits fully automatic 30

What to do next -Defend of DNS rebinding -PostMessage Mechanism -Make DOM based XSS DEMO -Find the ways to avoid the jeopardize 31

Reference s sessions/presentation/stock versalPDFXSS.ppt 32

Thank You ;) 10/

Questions?