CVE Vulnerabilities

CVE-2017-0170

Improper Restriction of XML External Entity Reference

Published: Jul 11, 2017 | Modified: Sep 27, 2017
CVSS 3.x
6.5
MEDIUM
Source:
NVD
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
CVSS 2.x
4.3 MEDIUM
AV:N/AC:M/Au:N/C:N/I:N/A:P
RedHat/V2
RedHat/V3
Ubuntu

Windows Performance Monitor in Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, Windows 10 Gold, 1511, 1607, 1703, and Windows Server 2016 allows an information disclosure vulnerability due to the way it parses XML input, aka Windows Performance Monitor Information Disclosure Vulnerability.

Weakness

The software 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.

Affected Software

Name Vendor Start Version End Version
Windows_10 Microsoft - -
Windows_10 Microsoft 1511 1511
Windows_10 Microsoft 1607 1607
Windows_10 Microsoft 1703 1703
Windows_7 Microsoft * *
Windows_8.1 Microsoft * *
Windows_server_2008 Microsoft * *
Windows_server_2008 Microsoft r2 r2
Windows_server_2012 Microsoft - -
Windows_server_2012 Microsoft r2 r2
Windows_server_2016 Microsoft * *

Extended Description

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.

Potential Mitigations

References