Vulnerabilities > CVE-2018-16738 - Improper Authentication vulnerability in multiple products

047910
CVSS 3.7 - LOW
Attack vector
NETWORK
Attack complexity
HIGH
Privileges required
NONE
Confidentiality impact
NONE
Integrity impact
LOW
Availability impact
NONE
network
high complexity
tinc-vpn
debian
starwindsoftware
CWE-287
nessus

Summary

tinc 1.0.30 through 1.0.34 has a broken authentication protocol, although there is a partial mitigation. This is fixed in 1.1.

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Authentication Abuse
    An attacker obtains unauthorized access to an application, service or device either through knowledge of the inherent weaknesses of an authentication mechanism, or by exploiting a flaw in the authentication scheme's implementation. In such an attack an authentication mechanism is functioning but a carefully controlled sequence of events causes the mechanism to grant access to the attacker. This attack may exploit assumptions made by the target's authentication procedures, such as assumptions regarding trust relationships or assumptions regarding the generation of secret values. This attack differs from Authentication Bypass attacks in that Authentication Abuse allows the attacker to be certified as a valid user through illegitimate means, while Authentication Bypass allows the user to access protected material without ever being certified as an authenticated user. This attack does not rely on prior sessions established by successfully authenticating users, as relied upon for the "Exploitation of Session Variables, Resource IDs and other Trusted Credentials" attack patterns.
  • Exploiting Trust in Client (aka Make the Client Invisible)
    An attack of this type exploits a programs' vulnerabilities in client/server communication channel authentication and data integrity. It leverages the implicit trust a server places in the client, or more importantly, that which the server believes is the client. An attacker executes this type of attack by placing themselves in the communication channel between client and server such that communication directly to the server is possible where the server believes it is communicating only with a valid client. There are numerous variations of this type of attack.
  • Utilizing REST's Trust in the System Resource to Register Man in the Middle
    This attack utilizes a REST(REpresentational State Transfer)-style applications' trust in the system resources and environment to place man in the middle once SSL is terminated. Rest applications premise is that they leverage existing infrastructure to deliver web services functionality. An example of this is a Rest application that uses HTTP Get methods and receives a HTTP response with an XML document. These Rest style web services are deployed on existing infrastructure such as Apache and IIS web servers with no SOAP stack required. Unfortunately from a security standpoint, there frequently is no interoperable identity security mechanism deployed, so Rest developers often fall back to SSL to deliver security. In large data centers, SSL is typically terminated at the edge of the network - at the firewall, load balancer, or router. Once the SSL is terminated the HTTP request is in the clear (unless developers have hashed or encrypted the values, but this is rare). The attacker can utilize a sniffer such as Wireshark to snapshot the credentials, such as username and password that are passed in the clear once SSL is terminated. Once the attacker gathers these credentials, they can submit requests to the web service provider just as authorized user do. There is not typically an authentication on the client side, beyond what is passed in the request itself so once this is compromised, then this is generally sufficient to compromise the service's authentication scheme.
  • 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 familyFreeBSD Local Security Checks
    NASL idFREEBSD_PKG_A4EB38EACC0611E8ADA4408D5CF35399.NASL
    descriptiontinc-vpn.org reports : The authentication protocol allows an oracle attack that could potentially be exploited. If a man-in-the-middle has intercepted the TCP connection it might be able to force plaintext UDP packets between two nodes for up to a PingInterval period.
    last seen2020-06-01
    modified2020-06-02
    plugin id118024
    published2018-10-10
    reporterThis script is Copyright (C) 2018-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/118024
    titleFreeBSD : tinc -- Buffer overflow (a4eb38ea-cc06-11e8-ada4-408d5cf35399)
  • NASL familyFedora Local Security Checks
    NASL idFEDORA_2018-AFAE5E8438.NASL
    descriptionSecurity fix for CVE-2018-16737, CVE-2018-16738, CVE-2018-16758 Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.
    last seen2020-06-05
    modified2019-01-03
    plugin id120712
    published2019-01-03
    reporterThis script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/120712
    titleFedora 29 : tinc (2018-afae5e8438)
  • NASL familyFedora Local Security Checks
    NASL idFEDORA_2018-31C2A0B2EA.NASL
    descriptionSecurity fix for CVE-2018-16737, CVE-2018-16738, CVE-2018-16758 Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.
    last seen2020-06-05
    modified2019-01-03
    plugin id120335
    published2019-01-03
    reporterThis script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/120335
    titleFedora 28 : tinc (2018-31c2a0b2ea)
  • NASL familyDebian Local Security Checks
    NASL idDEBIAN_DSA-4312.NASL
    descriptionSeveral vulnerabilities were discovered in tinc, a Virtual Private Network (VPN) daemon. The Common Vulnerabilities and Exposures project identifies the following problems : - CVE-2018-16738 Michael Yonli discovered a flaw in the implementation of the authentication protocol that could allow a remote attacker to establish an authenticated, one-way connection with another node. - CVE-2018-16758 Michael Yonli discovered that a man-in-the-middle that has intercepted a TCP connection might be able to disable encryption of UDP packets sent by a node.
    last seen2020-06-01
    modified2020-06-02
    plugin id117958
    published2018-10-09
    reporterThis script is Copyright (C) 2018-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/117958
    titleDebian DSA-4312-1 : tinc - security update