A vulnerability in the SOAP API of Cisco Data Center Network Manager (DCNM) could allow an authenticated, remote attacker to gain read access to information that is stored on an affected system. To exploit this vulnerability, an attacker would need administrative privileges on the DCNM application. The vulnerability exists because the SOAP API improperly handles XML External Entity (XXE) entries when parsing certain XML files. An attacker could exploit this vulnerability by inserting malicious XML content in an API request. A successful exploit could allow the attacker to read arbitrary files from the affected device. Note: The severity of this vulnerability is aggravated by the vulnerabilities described in the Cisco Data Center Network Manager Authentication Bypass Vulnerabilities advisory, published simultaneously with this one.
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 |
|---|---|---|---|
| Data_center_network_manager | Cisco | * | 11.3(1) (excluding) |
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.