Summary

Netsparker detected that BREACH (Browser Reconnaissance & Exfiltration via Adaptive Compression of Hypertext) attack is possible on this website.

Due to elements that make BREACH attack possible, SSL/TLS protected traffic remains vulnerable and can be attacked to uncover information from the website.

Regardless of which version of SSL/TLS you use, attacks are still possible. Attacks do not require TLS-layer compression and they can work against any cipher suite.

Impact

Even if you use an SSL/TLS protected connection, an attacker can still view the victim’s encrypted traffic (perhaps using ARP spoofing) and cause the victim to send HTTP requests to the vulnerable web server. Following these steps, an attacker could steal information from the website and do the following:

  • Inject partial plaintext they have uncovered into a victim's requests
  • Measure the size of encrypted traffic
Remediation

Netsparker reported a Possible BREACH Attack issue because the target web page meets the following conditions that facilitate it:

  • Served from a server that uses HTTP-level compression (ie. gzip)
  • Reflects user-input in the HTTP response bodies
  • Contains sensitive information (such as a CSRF token) in HTTP response bodies

To mitigate the issue, we recommend the following solutions:

 

  1. If possible, disable HTTP level compression
  2. Separate sensitive information from user input
  3. Protect vulnerable pages with CSRF token. The SameSite Cookie attribute will mitigate this issue, because to exploit this issue an attacker forces the victim to visit a target website using invisible frames. With the SameSite cookie attribute added, cookies that belong to the target won't be sent with a request that does not include top level navigation.
  4. Hide the length of the traffic by adding a random number of bytes to the responses.
  5. Add in a rate limit, so that the page maximum is reached five times per minute. 
Classifications
OWASP 2013-A9, OWASP 2017-A9 , CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
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