Web vulnerabilities, as we well know, are a malicious tool that cybercriminals frequently use, and one of them is CRLF injection. This vulnerability occurs when an attacker is able to inject data in a request to a server, due to the lack of input data filtering by the server. In this case, the affected web allows values to be passed directly to the Location, Set-Cookie, etc. response fields, without cleaning them, which in turn allows us various types of attack such as XSS, Cache-Poisoning, Cache-based defacement, page injection and many others.
How can CRLF Injection damage our PC?
Depending on how it plays out, this can be either a minor issue or a pretty serious security flaw. Let’s look at the latter because, after all, we must always be prepared for any threat. Suppose a file is used at some point to modify or just glance at the data in a record of some kind. If an attacker managed to drop a CRLF, then he can inject some kind of programmatic read method into the file. This could cause the contents to be written to the screen on the next attempt to use this file.
Another example is “response splitting” attacks, where CRLFs are injected into an application and included in the response. The additional CRLFs are interpreted by proxies, caches, and perhaps browsers as the end of a packet, causing chaos.
As we have always said in many other articles, the most effective method to avoid these is to apply filters on any data that enters our server or our website, examining and cleaning up the different variables that can take advantage of this CRLF vulnerability.
Although if we want to help ourselves in a more efficient way there are tools in charge of locating vulnerable points on our website, we can always use these automated vulnerability scanners that usually find this type of vulnerability.
See also:
SQL Injection – How these attacks can affect us
What should we know about security with JavaScript
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