Imagine you are comfortably surfing the Internet and click on a supposedly harmless link. Suddenly you end up on an unknown website that immediately starts tapping into your data. Unpleasant, isn’t it? That’s exactly what can happen when open redirects come into play. These inconspicuous vulnerabilities can cause huge problems – not only for individuals, but also for companies. In this article, we take a closer look at open redirects, explain how they work, highlight the associated risks and give you tips on how you can protect yourself.
Definition of Open Redirects
Open redirects are URL redirects that can be controlled without restrictions from external sources. Basically, these are links that redirect users to another website without being checked or verified. These redirects are particularly treacherous because they often appear harmless at first glance.
Why are they problematic?
Open redirects are problematic because they are a potential gateway for cybercriminals. They can be used to redirect users to malicious websites without them realizing it. This can lead to phishing attacks, malware infections and other security incidents. A supposedly harmless click on a link can quickly turn into a disaster.
How open redirects work
Technical explanation
An open redirect occurs when a website accepts parameters in the URL that determine where the user is redirected to without checking these parameters sufficiently. This can happen due to insecure programming or a lack of validation. Hackers can exploit this vulnerability by creating manipulated URLs that redirect the user to dangerous pages.
Technical example
Let’s look at a typical URL with an open redirect:
https://www.examplewebsite.com/redirect?url=https://www.evilwebsite.com
In this example, the user is redirected from examplewebsite.com to evilwebsite.com. The url parameter specifies the destination of the redirect. If the website examplewebsite.com does not check this parameter properly, attackers can manipulate the url parameter and thus redirect the user to any website.
A secure approach would be to only allow permitted URLs:
allowed_urls = ['https://www.erlaubtewebsite.com', 'https://www.partnersite.com']
redirect_url = request.GET.get('url')
if redirect_url in allowed_urls:
return redirect(redirect_url)
else:
return redirect('https://www.beispielwebsite.com/fehler')
In this code snippet, the desired URL is only redirected if it is included in the list of permitted URLs. Otherwise, the user is redirected to an error page. This simple validation prevents malicious URLs from being used as the target of the redirect.
Examples from practice
1. phishing attack on an email account
A user receives an email that appears to come from a trustworthy service provider such as a bank or a social network. The email contains a link that is supposed to lead to a page where the user can reset their password. However, an open redirect on the service provider’s website redirects the user to a phishing page that steals their access data.
2. manipulated advertisements
An advertising network uses open redirects to redirect users to various partner sites. An attacker infiltrates the network and changes the redirect URLs so that users are redirected to malware-distributing sites. The infected computers then become part of a botnet or users are blackmailed with ransomware.
3. fraud in online games
In a popular online game, fraudsters use open redirects to lure players to fake competition sites. These sites ask for players’ credentials or download malware that then takes over game accounts and steals virtual goods that are subsequently sold.
4. attacks on government websites
Cybercriminals use open redirects on official government websites to redirect citizens to fake websites that collect personal information or payment data. These attacks can have particularly serious consequences as they undermine public trust in government institutions.
Threats and risks
Abuse by cyber criminals
Cybercriminals use open redirects to redirect users to fake websites designed to steal personal information. This can take the form of phishing attacks, where victims are tricked into revealing their login details or other sensitive information.
Possible damage for users and websites
The damage caused by open redirects can be immense. Users can become victims of identity theft or financial losses. Websites that allow open redirects risk their reputation and lose the trust of their customers. They can also suffer legal consequences and financial losses.
Detection and prevention
How to identify open redirects on your own website
Regular security checks should be carried out to identify open redirects on your own website. Tools such as penetration tests and URL scanners can help to identify vulnerabilities. It is important to thoroughly validate and sanitize all inputs that affect URL redirects.
Protective measures and best practices
One of the best protective measures against open redirects is the implementation of strict validation and authentication processes. Redirects should only be allowed to pre-approved URLs. In addition, regular training and awareness-raising measures should be carried out for developers and users to emphasize the importance of security on the Internet.
Conclusion
Open redirects are a serious security threat that should not be underestimated. They offer cybercriminals an easy way to deceive users and steal data. It is crucial that companies and developers take the necessary measures to eliminate this vulnerability and protect their systems.
Call for regular security audits
Regular security audits and the implementation of best practices are essential to prevent open redirects. Only by continuously monitoring and improving security measures can companies minimize risk and protect their users from the dangers of cybercrime. Vulnerability management and targeted protective measures are essential to prevent hacker attacks and other security gaps.
