MIME Types Node

MIME (Multipurpose Internet Mail Extensions) is used on the internet to determine a file’s type. It is similar to file extensions in operating systems.

• Web Servers and browsers have a list of MIME types so they can identify files and take appropriate action. For example, if a file is a PDF, a browser may launch a relevant program so that you can see the content of this PDF file.
• Clients and servers use MIME type information to negotiate content. Clients send MIME type information of request through Content-type Header in HTTP Request and state which kind of output they want to consume by using MIME types in the accept header.

MIME contains two parts: type and subtype. A slash (/) is used between type and subtype, such as image/jpeg. You can’t always see an extension in URLs because modern web applications use SEO (Search Engine Optimization) friendly URLs. It isn’t always possible to deduce which type of file is served by looking at the URL. SEO-friendly URLs or API endpoints, for example, usually don't have extensions.

Open to XSS attacks

Cybercriminals can still use the MIME feature to attack web applications. If a web application allows users to upload data to the server, attackers can disguise a malicious file under a harmless file type. When a web browser renders this file, it can allow the attacker to carry out a cross-site scripting attack.

Acunetix 360 detects all files with the MIME type during scanning. This information is very useful in case further manual testing is required. It also helps security professionals spot any unusual files or types served by the server, which could indicate a successful hack.

• In addition to MIME-types listed in Knowledge Base, Acunetix 360 also reports the URLs that lack a MIME type. These URLs can cause MIME type sniffing threats if content is misinterpreted by browsers. Acunetix 360 reports Missing Content-Type Header issues for such cases.

Once the scan is completed, all MIME types are listed under the MIME Types node in the Knowledge Base. You can access the same information in the Knowledge Base Report and Knowledge Base Tab.

For further information, see Knowledge Base Nodes.

How to View the MIME Types Node in Acunetix 360

1. Log in to Acunetix 360.
2. From the main menu, click Scans, then Recent Scans. The Recent Scans window is displayed.
3. Next to the relevant website, click Report.
4. From the Technical Report section, click the Knowledge Base tab.
5. Click the MIME Types node. The information is displayed in a MIME Types tab.