Vulnerabilities > CVE-2018-8635 - Improper Input Validation vulnerability in Microsoft Sharepoint Enterprise Server and Sharepoint Server
Attack vector
NETWORK Attack complexity
LOW Privileges required
LOW Confidentiality impact
HIGH Integrity impact
HIGH Availability impact
HIGH Summary
An elevation of privilege vulnerability exists when Microsoft SharePoint Server does not properly sanitize a specially crafted authentication request to an affected SharePoint server, aka "Microsoft SharePoint Server Elevation of Privilege Vulnerability." This affects Microsoft SharePoint Server, Microsoft SharePoint.
Vulnerable Configurations
| Part | Description | Count |
|---|---|---|
| Application | 3 |
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Buffer Overflow via Environment Variables This attack pattern involves causing a buffer overflow through manipulation of environment variables. Once the attacker finds that they can modify an environment variable, they may try to overflow associated buffers. This attack leverages implicit trust often placed in environment variables.
- Server Side Include (SSI) Injection An attacker can use Server Side Include (SSI) Injection to send code to a web application that then gets executed by the web server. Doing so enables the attacker to achieve similar results to Cross Site Scripting, viz., arbitrary code execution and information disclosure, albeit on a more limited scale, since the SSI directives are nowhere near as powerful as a full-fledged scripting language. Nonetheless, the attacker can conveniently gain access to sensitive files, such as password files, and execute shell commands.
- Cross Zone Scripting An attacker is able to cause a victim to load content into their web-browser that bypasses security zone controls and gain access to increased privileges to execute scripting code or other web objects such as unsigned ActiveX controls or applets. This is a privilege elevation attack targeted at zone-based web-browser security. In a zone-based model, pages belong to one of a set of zones corresponding to the level of privilege assigned to that page. Pages in an untrusted zone would have a lesser level of access to the system and/or be restricted in the types of executable content it was allowed to invoke. In a cross-zone scripting attack, a page that should be assigned to a less privileged zone is granted the privileges of a more trusted zone. This can be accomplished by exploiting bugs in the browser, exploiting incorrect configuration in the zone controls, through a cross-site scripting attack that causes the attackers' content to be treated as coming from a more trusted page, or by leveraging some piece of system functionality that is accessible from both the trusted and less trusted zone. This attack differs from "Restful Privilege Escalation" in that the latter correlates to the inadequate securing of RESTful access methods (such as HTTP DELETE) on the server, while cross-zone scripting attacks the concept of security zones as implemented by a browser.
- Cross Site Scripting through Log Files An attacker may leverage a system weakness where logs are susceptible to log injection to insert scripts into the system's logs. If these logs are later viewed by an administrator through a thin administrative interface and the log data is not properly HTML encoded before being written to the page, the attackers' scripts stored in the log will be executed in the administrative interface with potentially serious consequences. This attack pattern is really a combination of two other attack patterns: log injection and stored cross site scripting.
- Command Line Execution through SQL Injection An attacker uses standard SQL injection methods to inject data into the command line for execution. This could be done directly through misuse of directives such as MSSQL_xp_cmdshell or indirectly through injection of data into the database that would be interpreted as shell commands. Sometime later, an unscrupulous backend application (or could be part of the functionality of the same application) fetches the injected data stored in the database and uses this data as command line arguments without performing proper validation. The malicious data escapes that data plane by spawning new commands to be executed on the host.
Nessus
| NASL family | Windows : Microsoft Bulletins |
| NASL id | SMB_NT_MS18_DEC_OFFICE_SHAREPOINT.NASL |
| description | The Microsoft Sharepoint Server installation on the remote host is missing security updates. It is, therefore, affected by multiple vulnerabilities : - An information disclosure vulnerability exists when Microsoft Excel software reads out of bound memory due to an uninitialized variable, which could disclose the contents of memory. An attacker who successfully exploited the vulnerability could view out of bound memory. Exploitation of the vulnerability requires that a user open a specially crafted file with an affected version of Microsoft Excel software. The security update addresses the vulnerability by properly initializing the affected variable. (CVE-2018-8627) - An elevation of privilege vulnerability exists when Microsoft SharePoint Server does not properly sanitize a specially crafted authentication request to an affected SharePoint server. An attacker who successfully exploited this vulnerability could execute malicious code on a vulnerable server in the context of the SharePoint application pool account. (CVE-2018-8635) - An information disclosure vulnerability exists where certain modes of the search function in Microsoft SharePoint Server are vulnerable to cross-site search attacks (a variant of cross-site request forgery, CSRF). When users are simultaneously logged in to Microsoft SharePoint Server and visit a malicious web page, the attacker can, through standard browser functionality, induce the browser to invoke search queries as the logged in user. While the attacker cant access the search results or documents as such, the attacker can determine whether the query did return results or not, and thus by issuing targeted queries discover facts about documents that are searchable for the logged-in user. The security update addresses the vulnerability by running the search queries in a way that doesnt expose them to this browser vulnerability. (CVE-2018-8580) - A remote code execution vulnerability exists in Microsoft PowerPoint software when the software fails to properly handle objects in memory. An attacker who successfully exploited the vulnerability could run arbitrary code in the context of the current user. If the current user is logged on with administrative user rights, an attacker could take control of the affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. (CVE-2018-8628) |
| last seen | 2020-06-01 |
| modified | 2020-06-02 |
| plugin id | 119686 |
| published | 2018-12-14 |
| reporter | This script is Copyright (C) 2018-2019 and is owned by Tenable, Inc. or an Affiliate thereof. |
| source | https://www.tenable.com/plugins/nessus/119686 |
| title | Security Updates for Microsoft Sharepoint Server (December 2018) |
| code | |