A vulnerability in the web-based management interface of Cisco Identity Services Engine (ISE) could allow an authenticated, remote attacker to access sensitive information, conduct a server-side request forgery (SSRF) attack through an affected device, or negatively impact the responsiveness of the web-based management interface itself. This vulnerability is due to improper handling of XML External Entity (XXE) entries when parsing certain XML files. An attacker could exploit this vulnerability by uploading a crafted XML file that contains references to external entities. A successful exploit could allow the attacker to retrieve files from the local system, resulting in the disclosure of confidential information. A successful exploit could also cause the web application to perform arbitrary HTTP requests on behalf of the attacker or consume memory resources to reduce the availability of the web-based management interface. To successfully exploit this vulnerability, an attacker would need valid Super Admin or Policy Admin credentials.
The product processes an XML document that can contain XML entities with URIs that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Identity_services_engine | Cisco | * | 3.2 (excluding) |
| Identity_services_engine | Cisco | 3.2 (including) | 3.2 (including) |
XML documents optionally contain a Document Type Definition (DTD), which, among other features, enables the definition of XML entities. It is possible to define an entity by providing a substitution string in the form of a URI. The XML parser can access the contents of this URI and embed these contents back into the XML document for further processing. By submitting an XML file that defines an external entity with a file:// URI, an attacker can cause the processing application to read the contents of a local file. For example, a URI such as “file:///c:/winnt/win.ini” designates (in Windows) the file C:\Winnt\win.ini, or file:///etc/passwd designates the password file in Unix-based systems. Using URIs with other schemes such as http://, the attacker can force the application to make outgoing requests to servers that the attacker cannot reach directly, which can be used to bypass firewall restrictions or hide the source of attacks such as port scanning. Once the content of the URI is read, it is fed back into the application that is processing the XML. This application may echo back the data (e.g. in an error message), thereby exposing the file contents.