In a nutshell, the vulnerability results from the fact that the .NET Framework does not validate the identity of the caller of a particular method when it is invoked by a particular object. This means that any caller can forge an identity to impersonate any other caller. The spoofing can be as simple as replying to a request or as complex as performing actions on the victim’s behalf. For example, an attacker can spoof the identity of another user to gain access to the victim’s account or to modify information on the victim’s behalf. The .NET Framework provides numerous types of objects that can be used to make such requests, such as the HttpWebRequest class. The HttpWebRequest class can be used to make requests of any kind, including requests to download and install software on the victim’s machine.
Mitigation Strategies:
- Addressing the exploit in the .NET Framework
- Using the HttpWebRequest class from a different process to make requests of any kind, including requests to download and install software on the victim's machine
What you can do to protect yourself?
The .NET Framework has been updated to address the vulnerability. Microsoft is advising customers and partners to apply the security update, but there are also some recommendations for mitigating the risk.
One of the most significant ways you can reduce your risk is by using two-factor authentication and two-step verification whenever possible. The two-factor authentication provides an additional layer of protection, making it harder for attackers to impersonate a user or gain access to a system.
Additionally, Microsoft recommends that customers and partners should deploy IPsec VPNs with IKEv2 and TLS 1.2 as well as use Windows Defender Advanced Threat Protection (Windows Defender ATP) solutions such as IPS and antimalware solutions on all systems.
Vulnerability Discovery and exploitation
The vulnerability is found in the implementation of a particular method, AddRequestFromString(), which takes an empty string for its argument. If a user sends a maliciously crafted request to the .NET Framework using this method, it will be accepted by the .NET Framework and executed. The vulnerability was discovered because of an implementation oversight that allowed for the possibility that user input is not validated before being passed to methods on objects that are used by the HttpWebRequest class.
Vulnerability details
The vulnerability is present when a user sends a request to another user's computer, server or service that ends up being processed by a vulnerable .NET Framework object. The developer of the vulnerable .NET class would have to be specifically designed to be vulnerable or they must just not care about security because they never validated their caller’s identity.
How to exploit the vulnerability?
In order to exploit the vulnerability, an attacker needs to be able to execute code on the victim’s machine. This can be achieved through several different means. The simplest is through a man-in-the-middle attack. Another way is by exploiting another vulnerability in the system that would allow an attacker to run code on the victim’s machine, such as one of the vulnerabilities that has already been exploited in the past. Finally, an attacker can download and install software on the victim’s machine to achieve this result. Once all of this has been accomplished, an attacker can use the resulting privilege escalation to impersonate any user on the system and perform any action they want.
Timeline
Published on: 08/09/2022 20:15:00 UTC
Last modified on: 08/12/2022 17:29:00 UTC