CVE Vulnerabilities

CVE-2018-8532

Improper Restriction of XML External Entity Reference

Published: Oct 10, 2018 | Modified: Nov 27, 2018
CVSS 3.x
5.5
MEDIUM
Source:
NVD
CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
CVSS 2.x
4.3 MEDIUM
AV:N/AC:M/Au:N/C:P/I:N/A:N
RedHat/V2
RedHat/V3
Ubuntu

An information disclosure vulnerability exists in Microsoft SQL Server Management Studio (SSMS) when parsing a malicious XMLA file containing a reference to an external entity, aka SQL Server Management Studio Information Disclosure Vulnerability. This affects SQL Server Management Studio 17.9, SQL Server Management Studio 18.0. This CVE ID is unique from CVE-2018-8527, CVE-2018-8533.

Weakness

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.

Affected Software

Name Vendor Start Version End Version
Sql_server_management_studio Microsoft 17.9 (including) 17.9 (including)
Sql_server_management_studio Microsoft 18.0 (including) 18.0 (including)

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