The ever-increasing reliance on technology requires proactive measures to identify and fix vulnerabilities that compromise the security of our applications. With emerging threats and new vulnerabilities being discovered daily, it is crucial to remain up-to-date and informed on the latest cybersecurity concerns. In this article, we will detail the CVE-2022-39021 vulnerability that affects the U-Office Force Login function and exposes users to potential phishing attacks.


Recently, the CVE-2022-39021 vulnerability was discovered in the U-Office Force Login function of web applications. This vulnerability allows an unauthenticated remote attacker to redirect the user to an arbitrary website using an Open Redirect exploit. If exploited, an attacker could potentially compromise user credentials and facilitate other malicious activities on the targeted user's system.

To understand this vulnerability, it is essential to understand Open Redirects. Essentially, an Open Redirect is a security flaw that allows an attacker to redirect a user from a trusted website to another website. This type of vulnerability is particularly dangerous as it helps attackers launch effective phishing attacks.

Exploit Details

The vulnerability resides in the force_login function and affects U-Office web applications. The attacker can exploit the vulnerability by crafting a malicious URL that includes a redirect parameter pointing to an attacker-controlled domain. When the victim clicks on the malicious link, they will be redirected to the attacker's website instead of the original intended website.

Here is a code snippet demonstrating the vulnerable force_login function

def force_login(request):
    redirect_url = request.GET.get('redirect', '/')
    if request.user.is_authenticated:
        return HttpResponseRedirect(redirect_url)
        login_url = reverse('accounts:login') + '?next=' + redirect_url
        return HttpResponseRedirect(login_url)

The problematic code lies in the line redirect_url = request.GET.get('redirect', '/'). The redirect parameter is not properly sanitized, allowing an attacker to input an arbitrary URL that leads to the Open Redirect vulnerability.

Example of a malicious URL exploiting this vulnerability

Original References

- CVE-2022-39021: U-Office Force Login Function - Open Redirect Vulnerability
- National Vulnerability Database (NVD) - CVE-2022-39021
- GitHub Security Advisory for U-Office Force Login Open Redirect

Mitigation and Remediation

To protect your web applications from this Open Redirect vulnerability (CVE-2022-39021), the following countermeasures are recommended:

1. Update your U-Office web application to the latest version containing the security patch. Check with the vendor for the software's specific update instructions.
2. Sanitize the redirect parameter to ensure it only allows URLs from trusted domains. Consider using a whitelist of allowed domains and verify that the parameter value belongs to that list.


def is_allowed_domain(url):
    parsed_url = urlparse(url)
    return parsed_url.netloc in ALLOWED_REDIRECT_DOMAINS

def force_login(request):
    redirect_url = request.GET.get('redirect', '/')
    if not is_allowed_domain(redirect_url):
        redirect_url = '/'

3. Educate users about the dangers of clicking on suspicious links and the importance of verifying the authenticity of URLs before providing sensitive information.


CVE-2022-39021 highlights the importance of ensuring the security of web applications to protect user data and prevent malicious attacks. By understanding the vulnerability, implementing proper coding practices, and educating users about potential threats, organizations can drastically reduce the risk of successful cyber-attacks. Stay informed on the latest security vulnerabilities, and always apply recommended patches and updates to maintain a secure and robust application environment.


Published on: 10/31/2022 07:15:00 UTC