CVE-2022-35507 Scanner

The Proxmox Virtual Environment (PVE) and Proxmox Mail Gateway (PMG) are widely used virtualization management platforms enabling users to easily deploy and manage virtual machines and containers. Built to be robust and scalable, they are often employed by organizations seeking to efficiently utilize computing resources in both data centers and smaller environments. Proxmox VE offers features such as high availability, storage replication, and a web-based management interface, making it a comprehensive solution for IT infrastructure. The Proxmox Mail Gateway acts as a mail proxy to protect infrastructure from email threats, including spam and viruses. Collectively, these tools provide essential support for businesses aiming to maintain secure and effective networked systems. They are favored for their open-source nature, offering flexibility and customization options for various deployment needs.

CRLF Injection, also known as HTTP Response Splitting, is a vulnerability allowing attackers to craft input containing CRLF characters (carriage return and line feed) to manipulate HTTP responses. The vulnerability can be exploited to inject arbitrary HTTP headers by incorporating special characters in the input fields processed by the application. This issue can lead to diverse attack vectors, including web cache poisoning, cross-site scripting (XSS), and session fixation. Due to improper input validation, attackers can influence server responses, impacting browser behavior and potentially causing denial of service. The vulnerability particularly affects environments where headers are improperly constructed or escaped. This type of injection can be a stepping stone to executing more complex attacks by controlling HTTP header content.

The CRLF Injection vulnerability in Proxmox arises from the web interface allowing response-header manipulation via %%%%0d sequences. This flaw permits remote attackers to inject headers, which can deceive browsers into executing unintended directives. The attack affects web clients by allowing potentially harmful cookies to be set or manipulated, leading to denial-of-service conditions in specific browsers, notably those based on Chromium. The vulnerable endpoint is within the HTTP server component, where crafted requests containing CRLF characters can alter response headers. The manifestation of this vulnerability is through the ability of an attacker to find injection points where header information is processed without sufficient security checks. The presence of this flaw underscores the need for thorough input sanitization mechanisms within the HTTP handling modules.

When exploited, CRLF Injection vulnerabilities can cause significant disruptions. Attackers can leverage this weakness to execute cache poisoning attacks by altering the responses that caching servers store, leading to incorrect content being served to users. Additionally, it can enable cross-site scripting attacks when malicious scripts are injected into redirected pages through crafted headers, compromising client-side security. The manipulation of cookies can disrupt user sessions, hijack accounts, or log users out forcibly, affecting the application's integrity and user experience. Organizations with impacted services might face downtime or reputation damage if attackers exploit this flaw to conduct wide-scale denial-of-service attacks. Thus, prompt remediation is crucial to avoid such detrimental impacts.

REFERENCES

• https://git.proxmox.com/?p=pve-http-server.git%%%%3Ba=commitdiff%%%%3Bh=936007ae0241811093155000486da171379c23c2
• https://github.com/advisories/GHSA-xfgp-gpjw-wmqr
• https://starlabs.sg/blog/2022/12-multiple-vulnerabilites-in-proxmox-ve--proxmox-mail-gateway/#bug-0x02-crlf-injection-in-response-headers