Vulnerabilities > CVE-2021-46825 - HTTP Request Smuggling vulnerability in Broadcom Advanced Secure Gateway and Proxysg

047910
CVSS 9.1 - CRITICAL
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
HIGH
Integrity impact
HIGH
Availability impact
NONE
network
low complexity
broadcom
CWE-444
critical

Summary

Symantec Advanced Secure Gateway (ASG) and ProxySG are susceptible to an HTTP desync vulnerability. When a remote unauthenticated attacker and other web clients communicate through the proxy with the same web server, the attacker can send crafted HTTP requests and cause the proxy to forward web server responses to unintended clients. Severity/CVSSv3: High / 8.1 AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

Common Attack Pattern Enumeration and Classification (CAPEC)

  • HTTP Request Splitting
    HTTP Request Splitting (also known as HTTP Request Smuggling) is an attack pattern where an attacker attempts to insert additional HTTP requests in the body of the original (enveloping) HTTP request in such a way that the browser interprets it as one request but the web server interprets it as two. There are several ways to perform HTTP request splitting attacks. One way is to include double Content-Length headers in the request to exploit the fact that the devices parsing the request may each use a different header. Another way is to submit an HTTP request with a "Transfer Encoding: chunked" in the request header set with setRequestHeader to allow a payload in the HTTP Request that can be considered as another HTTP Request by a subsequent parsing entity. A third way is to use the "Double CR in an HTTP header" technique. There are also a few less general techniques targeting specific parsing vulnerabilities in certain web servers.
  • HTTP Request Smuggling
    HTTP Request Smuggling results from the discrepancies in parsing HTTP requests between HTTP entities such as web caching proxies or application firewalls. Entities such as web servers, web caching proxies, application firewalls or simple proxies often parse HTTP requests in slightly different ways. Under specific situations where there are two or more such entities in the path of the HTTP request, a specially crafted request is seen by two attacked entities as two different sets of requests. This allows certain requests to be smuggled through to a second entity without the first one realizing it.