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Security Advisories Relating to Symantec Products - Symantec Norton Client DLL Pre-Loading Uncontrolled Search Path Elevation of Privilege


November 17, 2016

Overview | Issues | Affected Products | Mitigation | Best Practices | Acknowledgements | Revisions




Norton Security products, Symantec Endpoint Protection Small Business Edition (SEP SBE) clients, and Symantec Endpoint Protection Small Business Edition Cloud (SEP SBE Cloud) clients are susceptible to a potential DLL pre-loading issue. The issue is caused by improper restrictions when system libraries are loaded. This could result in arbitrary code running with user-level permissions but may result in arbitrary code running with elevated permissions.



Highest severity issue: High
Number of issues: 1


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This update applies to the following issues:




Symantec Norton Client DLL Pre-Loading Uncontrolled Search Path Elevation of Privilege




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Symantec has verified the issues and addressed them in product updates as outlined below.



The following Norton products are affected.



Norton Family




Updated via Live Update to 22.7 or later


Norton Antivirus

Norton AntiVirus with Backup

Norton Security

Norton Security with Backup

Norton Internet Security

Norton 360


Symantec Small Business Edition

The following Symantec Small Business Edition products are affected.



Symantec Endpoint Protection Small Business Edition Workstation Clients



Updated workstation clients via Live Update to or later


Symantec Endpoint Protection Small Business Edition Cloud Workstation Clients


NOTE: Only SEP SBE/SBE Cloud workstation clients are impacted by this issue. SEP SBE/SBE Cloud servers are NOT affected.

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Symantec Norton Client DLL Pre-Loading Uncontrolled Search Path Elevation of Privilege


BID: 94295

Severity: High (CVSSv3: 7.5) AV:L/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H

Impact: Privilege escalation

Exploitation: None

Norton products and SEPSBE/SEPSBE Cloud workstation clients are susceptible to a potential DLL-preloading issue resulting from improper path restrictions. This could cause one of the application libraries to explicitly load a third-party system DLL without specifying an absolute path. An authorized but malicious user with access to a client could potentially insert a specially crafted file using the same name as the specified DLL into one of the susceptible folders or a network share. In most situations, the arbitrary code would run with user-level privileges. However, during installation or uninstallation processes, arbitrary code could run with system privileges. A remote attack against this vulnerability could potentially leverage known methods of trust exploitations to compromise a client user. This could allow the attacker to possibly gain unauthorized access to the computer. Such attempts generally require a user to access a malicious link through a website or an HTTP email in order to download malicious content.


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Product engineers have addressed this vulnerability through a client update delivered to Norton products and SEP SBE/SEP SBE Cloud workstation clients via LiveUpdate along with normal definition and signature updates. Norton customers should ensure they are running 22.7 or later. SEP SBE and SEP SBE Cloud customers should ensure workstation clients are running or later.


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Symantec recommends the following measures to reduce risk of attack:

  • Restrict access to administrative or management systems to authorized privileged users
  • Restrict remote access to trusted/authorized systems only
  • Run under the principle of least privilege, where possible, to limit the impact of potential exploit
  • Keep all operating systems and applications current with vendor patches
  • For SEP Small Business Edition/SEP Cloud clients, follow a multilayered approach to security. At a minimum, run both firewall and antimalware applications to provide multiple points of detection and protection to both inbound and outbound threats.
  • Deploy network and host-based intrusion detection systems to monitor network traffic for signs of anomalous or suspicious activity. This may aid in the detection of attacks or malicious activity related to the exploitation of latent vulnerabilities.


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  • Herman Groeneveld, aka Sh4d0wman, of firstlink.nl (CVE-2016-5311)



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  • 11/23/2016 - Modified the Symantec Endpoint Protection Small Business Edition products to reflect the proper naming convention. Clarified advisory to show that for SEP SBE and SEP SBE Cloud, only the workstation clients are impacted by this issue. SEP SBE and SEP SBE Cloud servers are not affected and do not required updating.



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Symantec takes the security and proper functionality of our products very seriously. As founding members of the Organization for Internet Safety (OISafety), Symantec supports and follows responsible disclosure guidelines.
Symantec has developed a Software Security Vulnerability Management Process document outlining the process we follow in addressing suspected vulnerabilities in our products.
Symantec Corporation firmly believes in a proactive approach to secure software development and implements security review into various stages of the software development process. Additionally, Symantec is committed to the security of its products and services as well as to its customers’ data. Symantec is committed to continually improving its software security process.
This document provides an overview of the current Secure Development Lifecycle (SDLC) practice applicable to Symantec’s product and service teams as well as other software security related activities and policies used by such teams. This document is intended as a summary and does not represent a comprehensive list of security testing and practices conducted by Symantec in the software development process.
Please contact secure@symantec.com if you believe you have discovered a security issue in a Symantec product. A member of the Symantec Software Security team will contact you regarding your submission to coordinate any required response. Symantec strongly recommends using encrypted email for reporting vulnerability information to secure@symantec.com.
The Symantec Software Security PGP key can be found at the following location:
Permission to redistribute this alert electronically is granted as long as it is not edited in any way unless authorized by Symantec Software Security. Reprinting the whole or part of this alert in any medium other than electronically requires permission from secure@symantec.com.
Last modified on: November 17, 2016
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