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session:extra:heartbleed-poc [2014/07/31 11:16]
vladum [Exploit] 		session:extra:heartbleed-poc [2020/07/19 12:49] (current)
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-= Extra - Heartbleed PoC+====== 0x0Cb. Heartbleed Proof of Concept ======
  
-== Information Leak Attacks+===== Information Leak =====
  
-== Environment Setup+In the context of binary exploitation, information leakage attacks are based on bugs such as integers overflows, or unchecked bounds, and can be used to leak the memory contents of a process. Using this kind of attack we can overcome some protection mechanism that we just studied. We could leak stack canaries and then use them to successfully overflow the stack, or we could leak addresses from the stack or other structures, thus defeating ASLR.
  
-We are going to setup a minimal vulnerable environment to experiment with the exploit. We need a vulnerable OpenSSL version and a webserver. We also need to configure a basic website that will just serve a static page.+More generally, this class of attacks includes any method that leads to the exposure of secret information (e.g., documents, keys). Besides software bugs, things like too much logging can also count as information leakage. For example, leaving the debug logging output of your web application can result in leaking paths on the hosting machine that can later be used in attacks.
  
-=== Download Nginx & OpenSSL+A very famous and recent bug that leaks memory content is Heartbleed. The vulnerability was discovered in OpenSSL's code, and is a very trivial memory copy between 2 buffers with an unsanitized length parameter given as input by the user. Using this, the attacker can leak any secrets kept in a webserver's memory during operation, including, but not limited to: 
 +  * encryption keys 
 +  * passwords 
 +  * session cookies 
 +  * personal identifiable information (e.g., credit card numbers) 
 + 
 +This section will go through a Proof-of-Concept exploit that will enable us to leak a normal user's session cookie for a vulnerable server (localhost). 
 +===== Environment Setup ===== 
 + 
 +To setup a minimal environment, we need a vulnerable OpenSSL version and a webserver. We also need to configure a basic website that will just serve a static page. 
 + 
 +==== Download Nginx & OpenSSL ====
  
   * [[https://www.openssl.org/source/openssl-1.0.1f.tar.gz|OpenSSL 1.0.1f Source]]   * [[https://www.openssl.org/source/openssl-1.0.1f.tar.gz|OpenSSL 1.0.1f Source]]
   * [[http://nginx.org/download/nginx-1.6.0.tar.gz|Nginx 1.6.0 Source]]   * [[http://nginx.org/download/nginx-1.6.0.tar.gz|Nginx 1.6.0 Source]]
  
-=== Compile Nginx & vulnerable OpenSSL+==== Compile Nginx & vulnerable OpenSSL ====
  
 <code bash> <code bash>
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 **Continue from here if your Perl version is older than 5.18.X.** **Continue from here if your Perl version is older than 5.18.X.**
 +
 +Note that we are only building Nginx, which will take care of running ''make'' in the OpenSSL directory for us.
  
 <code text> <code text>
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 </code> </code>
  
-=== Basic SSL website+==== Basic SSL website ====
  
 Prepare a self-signed certificate: Prepare a self-signed certificate:
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 sudo chown vladum: /usr/share/nginx/www sudo chown vladum: /usr/share/nginx/www
 echo “Hello” > /usr/share/nginx/www/index.html echo “Hello” > /usr/share/nginx/www/index.html
 +</code>
 +
 +Start the server:
 +
 +<code bash>
 +~$ ~/vuln/sbin/nginx
 </code> </code>
  
 You should see the page live at https://127.0.0.1:11443. Ignore the certificate warning. You should see the page live at https://127.0.0.1:11443. Ignore the certificate warning.
  
-== Vulnerability+===== Vulnerability =====
  
 General information about this vulnerability can be obtained from [[http://heartbleed.com/|this website]]. General information about this vulnerability can be obtained from [[http://heartbleed.com/|this website]].
  
-The TLS Heartbeat protocol extension (see [[http://tools.ietf.org/html/rfc6520|RFC 6520]] specifies a keep-alive functionality between a TLS client and server that uses 2 messages: a request and the response. The RFC mandates the following:+The TLS Heartbeat protocol extension (see [[http://tools.ietf.org/html/rfc6520|RFC 6520]]) specifies a keep-alive functionality between a TLS client and server that uses 2 messages: a request and the response. The RFC mandates the following:
  
 <code text> <code text>
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 If the attacker sends a ''payload'', but a bogus, big, ''payload_length'', the vulnerable routine will copy past the end of the buffer and leak memory contents. Since the ''payload_length'' field is represented on 2 bytes, 64KB can be leaked. If the attacker sends a ''payload'', but a bogus, big, ''payload_length'', the vulnerable routine will copy past the end of the buffer and leak memory contents. Since the ''payload_length'' field is represented on 2 bytes, 64KB can be leaked.
  
-== Exploit+===== Exploit =====
  
 A TLS channel is established after the initial handshake part of the protocol. Since the Heartbeat RFC specifies the a Heartbeat Request can be send at any time, we simply have to initiate a TLS connection with a ''ClientHello'' message (first step of the handshake), and the send the bogus Heartbeat Request. A TLS channel is established after the initial handshake part of the protocol. Since the Heartbeat RFC specifies the a Heartbeat Request can be send at any time, we simply have to initiate a TLS connection with a ''ClientHello'' message (first step of the handshake), and the send the bogus Heartbeat Request.
session/extra/heartbleed-poc.1406794576.txt.gz · Last modified: 2014/07/31 11:16 by vladum

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