ID CVE-2015-7755
Summary Juniper ScreenOS 6.2.0r15 through 6.2.0r18, 6.3.0r12 before 6.3.0r12b, 6.3.0r13 before 6.3.0r13b, 6.3.0r14 before 6.3.0r14b, 6.3.0r15 before 6.3.0r15b, 6.3.0r16 before 6.3.0r16b, 6.3.0r17 before 6.3.0r17b, 6.3.0r18 before 6.3.0r18b, 6.3.0r19 before 6.3.0r19b, and 6.3.0r20 before 6.3.0r21 allows remote attackers to obtain administrative access by entering an unspecified password during a (1) SSH or (2) TELNET session.
Vulnerable Configurations
  • Juniper Networks ScreenOS 6.3.0 R17
  • Juniper Networks ScreenOS 6.3.0 R18
  • Juniper Networks ScreenOS 6.3.0 R19
  • Juniper Networks ScreenOS 6.3.0 R20
Base: 10.0 (as of 21-12-2015 - 10:25)
  • 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.
metasploit via4
description This module scans for the Juniper SSH backdoor (also valid on Telnet). Any username is required, and the password is <<< %s(un='%s') = %u.
last seen 2019-03-13
modified 2018-08-15
published 2016-03-30
reliability Normal
reporter Rapid7
title Juniper SSH Backdoor Scanner
nessus via4
  • NASL family Default Unix Accounts
    description The account 'netscreen' on the remote host has the password '<<< %s(un='%s') = %u', a known backdoor password. The affected devices are firewalls and VPN gateways. A remote attacker can exploit this vulnerability to gain administrative access and monitor network traffic, deny network access, and alter device and firewall configurations.
    last seen 2019-02-21
    modified 2018-07-27
    plugin id 87601
    published 2015-12-23
    reporter Tenable
    title Juniper ScreenOS SSH / Telnet Authentication Backdoor
  • NASL family Firewalls
    description The remote host is running a version of Juniper ScreenOS that is 6.2.x prior to 6.2.0r19 or 6.3.x prior to 6.3.0r21. It is, therefore, affected by multiple vulnerabilities : - A backdoor exists that allows a remote attacker administrative access to the device over SSH or telnet. (CVE-2015-7755) - An unspecified flaw exists that allows a man-in-the-middle attacker to decrypt VPN traffic. (CVE-2015-7756) Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.
    last seen 2019-02-21
    modified 2018-09-17
    plugin id 87507
    published 2015-12-18
    reporter Tenable
    title Juniper ScreenOS 6.2.0r15 < 6.2.0r19 / 6.3.0r12 < 6.3.0r21 Multiple Vulnerabilities (JSA10713)
refmap via4
bid 79626
cert-vn VU#640184
sectrack 1034489
Last major update 07-12-2016 - 13:25
Published 19-12-2015 - 09:59
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