Vulnerability identifier: #VU29910
Vulnerability risk: Medium
CVSSv3.1: 6 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N/E:U/RL:U/RC:C]
CVE-ID:
CWE-ID:
CWE-444
Exploitation vector: Network
Exploit availability: No
Vulnerable software:
Windows
Operating systems & Components /
Operating system
Windows Server
Operating systems & Components /
Operating system
Microsoft IIS
Server applications /
Web servers
Vendor: Microsoft
Description
The vulnerability allows a remote attacker to perform HTTP request smuggling attack.
The vulnerability exists due to the way that HTTP proxies (front-end) and web servers (back-end) that do not strictly adhere to RFC standards handle sequences of HTTP requests received from multiple sources. A remote attacker can send a specially crafted request to a targeted IIS Server, perform HTTP request smuggling attack and modify responses or retrieve information from another user's HTTP session.
Mitigation
Cybersecurity Help is currently unaware of any official solution to address this vulnerability.
Microsoft recommends that administrators review front-end environmental configurations, and if necessary, enable the request smuggling filter. Testing is required to determine that front-end load balancers and proxies do not forward malformed requests; these requests will be rejected when the filter is enabled, and may disrupt communications.
Enable the request smuggling filter on your web server by using the Registry Editor
Note Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. For information about how to edit the registry, view the "Changing Keys and Values" Help topic in Registry Editor (Regedit.exe) or view the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe.
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\HTTP\Parameters
Vulnerable software versions
Windows: 10 - 10 2004, 7, 8.1 - 8.1 RT
Windows Server: 2008 R2 - 2019 2004
Microsoft IIS: 7.5 - 10.0
External links
http://portal.msrc.microsoft.com/en-US/security-guidance/advisory/ADV200008
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.