Vulnerabilities > CVE-2017-11786 - Authentication Bypass by Capture-replay vulnerability in Microsoft Lync and Skype for Business
Attack vector
NETWORK Attack complexity
LOW Privileges required
NONE Confidentiality impact
HIGH Integrity impact
HIGH Availability impact
HIGH Summary
Skype for Business in Microsoft Lync 2013 SP1 and Skype for Business 2016 allows an attacker to steal an authentication hash that can be reused elsewhere, due to how Skype for Business handles authentication requests, aka "Skype for Business Elevation of Privilege Vulnerability."
Vulnerable Configurations
| Part | Description | Count |
|---|---|---|
| Application | 2 |
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Session Sidejacking Session sidejacking takes advantage of an unencrypted communication channel between a victim and target system. The attacker sniffs traffic on a network looking for session tokens in unencrypted traffic. Once a session token is captured, the attacker performs malicious actions by using the stolen token with the targeted application to impersonate the victim. This attack is a specific method of session hijacking, which is exploiting a valid session token to gain unauthorized access to a target system or information. Other methods to perform a session hijacking are session fixation, cross-site scripting, or compromising a user or server machine and stealing the session token.
- Reusing Session IDs (aka Session Replay) This attack targets the reuse of valid session ID to spoof the target system in order to gain privileges. The attacker tries to reuse a stolen session ID used previously during a transaction to perform spoofing and session hijacking. Another name for this type of attack is Session Replay.
- Man in the Middle Attack This type of attack targets the communication between two components (typically client and server). The attacker places himself in the communication channel between the two components. Whenever one component attempts to communicate with the other (data flow, authentication challenges, etc.), the data first goes to the attacker, who has the opportunity to observe or alter it, and it is then passed on to the other component as if it was never intercepted. This interposition is transparent leaving the two compromised components unaware of the potential corruption or leakage of their communications. The potential for Man-in-the-Middle attacks yields an implicit lack of trust in communication or identify between two components.
Nessus
| NASL family | Windows : Microsoft Bulletins |
| NASL id | SMB_NT_MS17_OCT_SKYPE.NASL |
| description | The Microsoft Skype for Business or Microsoft Lync installation on the remote host is missing a security update. It is, therefore, affected by the following vulnerability : - An elevation of privilege vulnerability exists when Skype for Business fails to properly handle specific authentication requests. An authenticated attacker who successfully exploited this vulnerability could steal an authentication hash that can be reused elsewhere. The attacker could then take any action that the user had permissions for, causing possible outcomes that could vary between users. (CVE-2017-11786) |
| last seen | 2020-06-01 |
| modified | 2020-06-02 |
| plugin id | 103753 |
| published | 2017-10-10 |
| reporter | This script is Copyright (C) 2017-2019 and is owned by Tenable, Inc. or an Affiliate thereof. |
| source | https://www.tenable.com/plugins/nessus/103753 |
| title | Security Updates for Microsoft Skype for Business and Microsoft Lync (October 2017) |
| code | |