Knowledge Center

McAfee Security Bulletin - Multiple McAfee product updates fix Linux kernel vulnerability “SegmentSmack” (CVE-2018-5390)
Security Bulletins ID:   SB10249
Last Modified:  2/26/2019


First Published: September 12, 2018
Impact of Vulnerability: CWE-controlled release: Uncontrolled Resource Consumption ('Resource Exhaustion')
CVE ID CVE-2018-5390
Severity Rating High
Base Score
Recommendations: Deploy product updates as they are made available.
Affected Software: Advanced Threat Defense (ATD)
Data Exchange Layer (DXL)
Data Loss Prevention (DLP) Monitor
Data Loss Prevention (DLP) Prevent
McAfee Active Response (MAR)
McAfee Email Gateway (MEG)
McAfee Linux Operating System (MLOS)
McAfee Web Gateway (MWG)
Network Security Manager (NSM) Linux
Threat Intelligence Exchange (TIE) Server
Location of updated software: http://www.mcafee.com/us/downloads/downloads.aspx
To receive email notification when this Security Bulletin is updated, click Subscribe on the right side of the page. To subscribe, you must be logged on.
Article contents: Vulnerability Description
A Linux kernel flaw known as SegmentSmack allows remote attackers to cause a denial-of-service using specially crafted TCP packets. A continuous two-way TCP session to a reachable open port is required to maintain the denial-of-service condition, so a spoofed IP address cannot be used to carry out the attack.

Linux kernel versions 4.9+ can be forced to make expensive calls to tcp_collapse_ofo_queue() and tcp_prune_ofo_queue() for every incoming packet, which can lead to a denial-of-service.
McAfee Product Vulnerability Status
McAfee produces several security appliances that ship with a Linux operating system. These appliances are potentially vulnerable to the kernel flaw described in this Security Bulletin. Investigation into all McAfee products is ongoing. This Security Bulletin will be updated as additional information is available. Not every version of the "Vulnerable and Updated" products are vulnerable. See the Product-Specific Notes section below for details. Products not on these lists are being investigated. 
Vulnerable and Updated
  • Advanced Threat Defense (ATD)
  • Data Exchange Layer (DXL)
  • McAfee Active Response (MAR)
  • McAfee Linux Operating System (MLOS)
  • Network Security Manager (NSM) Linux
  • McAfee Web Gateway (MWG)
  • Data Loss Prevention (DLP) Monitor
  • Data Loss Prevention (DLP) Prevent
  • SIEM
  • Threat Intelligence Exchange (TIE) Server
Not Vulnerable
  • Data Loss Prevention Endpoint (DLP Endpoint) / Host Data Loss Prevention (HDLP)
  • Endpoint Security (ENS)
  • ePolicy Orchestrator (ePO)
  • Host Intrusion Prevention Services (Host IPS)
  • McAfee Agent (MA)
  • McAfee Email Gateway (MEG)
  • Network Security Platform (NSP) Azure VM
  • Network Security Platform (NSP) Hardware Appliances
  • Network Threat Behavior Analysis (NTBA)
  • VirusScan Enterprise for Storage (VSES)
  • Other McAfee products that do not ship with a Linux operating system
For a description of each product, see: http://www.mcafee.com/us/apps/products-az.aspx
To remediate this issue, go to the Product Downloads site and download the applicable product update/hotfix files:
Product Versions Type File Name Release Date
ATD 4.6.0 Update migration- November 13, 2018
DXL 5.0.1 Update DXL Platform 5.0.1 Version February 26, 2019
DXL 4.1.2 Hotfix 1 (HF1) Hotfix DXL Platform 4.1.2 HF1 Version January 23, 2019
MAR MAR 2.3.0 HF3 (MAR Server Bundle version - includes MAR Server and Platform packages Hotfix MAR-Server-Bundle_2.3.0_Build_171_(ENU-RELEASE-MAIN).zip September 4, 2018
MLOS2 MLOS2 kernel-4.9.116 Maintenance Release kernel-4.9.116-1.mlos2.x86_64.rpm August 3, 2018
MLOS3 MLOS3 kernel-4.9.116 Maintenance Release kernel-4.9.116-1.mlos3.x86_64.rpm August 3, 2018
MWG build 26804 Main Release mwgappl- September 11, 2018
MWG build 26803 General Availability mwgappl- September 11, 2018
DLP Monitor 11.0.600-3489.103 Update McAfee-MS-11.0.600-3489.103.iso October 2, 2018
DLP Prevent 11.0.600-3489.103 Update McAfee-PS-11.0.600-3489.103.iso October 2, 2018
NSM Linux NSM_MLOS- Version 3.30 Hotfix NSM_MLOS- August 31, 2018
SIEM 10.3.3 Update NOTE: Choose the correct file for the appliance type.

November 13, 2018
TIE Server TIE Server 2.3.0 General Availability TIEServer_2.3.0.328_MARServer_2.4.0.158.x86_64-MAIN.ova September 25, 2018
Download and Installation Instructions
See KB56057 for instructions on how to download McAfee products, documentation, security updates, updates, and hotfixes. Review the Release Notes and the Installation Guide, which you can download from the Documentation tab, for instructions on how to install these updates.
Product-Specific Notes
In addition to the kernel updates, the packages include Intel® Microcode updates:
microcode   = (MLOS2) intel-ucode-20180807-2.mlos2.x86_64.rpm
                     = (MLOS3) intel-ucode-20180807-2.mlos3.x86_64.rpm
Kernel and microcode updates must both be applied. The above are the minimum versions for the fixes, but when updating, always take the latest package.

Network Security Platform:
Network Security Platform Hardware Appliances are not vulnerable. The recommendation for all Network Security Platform Virtual deployments is for the underlying host systems to be updated. Network Security Manager Linux appliance is vulnerable and requires the MLOS version hotfix indicated in the remediation table.

To mitigate SegmentSmack, you can add the following to your bootup process:
## turn on mitigation
$ SetSmack.sh low
## this is the script
$ cat SetSmack.sh
if [ "x$1" == "xlow" ]; then
    echo Setting limits low:
    sysctl -w net.ipv4.ipfrag_low_thresh=196608
    sysctl -w net.ipv4.ipfrag_high_thresh=262144
    sysctl -w net.ipv6.ip6frag_low_thresh=196608
    sysctl -w net.ipv6.ip6frag_high_thresh=262144
elif [ "x$1" == "xdef" ]; then
    echo Setting limits default:
    sysctl -w net.ipv4.ipfrag_high_thresh=4194304
    sysctl -w net.ipv4.ipfrag_low_thresh=3145728
    sysctl -w net.ipv6.ip6frag_high_thresh=4194304
    sysctl -w net.ipv6.ip6frag_low_thresh=3145728
echo Current values:
sysctl net.ipv4.ipfrag_low_thresh
sysctl net.ipv4.ipfrag_high_thresh
sysctl net.ipv6.ip6frag_low_thresh
sysctl net.ipv6.ip6frag_high_thresh
No vulnerability detection signatures are available.
This vulnerability was disclosed by The MITRE Corporation as a CVE.
Frequently Asked Questions (FAQs)
How do I know if my McAfee product is vulnerable or not?
For Endpoint products:
Use the following instructions for endpoint or client-based products:
  1. Right-click on the McAfee tray shield icon on the Windows taskbar.
  2. Select Open Console.
  3. In the console, select Action Menu.
  4. In the Action Menu, select Product Details. The product version is displayed.
For ePO/Server products:
Use the following instructions for server-based products:
  • Check the version and build of ePO that is installed. For information about how to check the version, see: KB52634.
  • Create a query in ePO for the product version of the product installed within your organization.
For Appliances:
Use the following instructions for Appliance-based products:
  1. Open the Administrator's User Interface (UI).
  2. Click the About link. The product version is displayed.
For DLP Endpoint ePO Extension:
Use the following instructions:
  1. Log on to your ePO server.
  2. Click Menu, Data Protection, DLP Policy.
  3. Inside the DLP console click Help, About. The product version is displayed.
What is CVSS?
CVSS, or Common Vulnerability Scoring System, is the result of the National Infrastructure Advisory Council's effort to standardize a system of assessing the criticality of a vulnerability. This system offers an unbiased criticality score between 0 and 10 that customers can use to judge how critical a vulnerability is and plan accordingly. For more information, visit the CVSS website at: http://www.first.org/cvss/.
When calculating CVSS scores, McAfee has adopted a philosophy that fosters consistency and repeatability. Our guiding principle for CVSS scoring is to score the exploit under consideration by itself. We consider only the immediate and direct impact of the exploit under consideration. We do not factor into a score any potential follow-on exploits that might be made possible by the successful exploitation of the issue being scored.
What are the CVSS scoring metrics?

CVE-2018-5390: SegmentSmack
Base Score 7.5
Attack Vector (AV) Network (N)
Attack Complexity (AC) Low (L)
Privileges Required (PR) None (N)
User Interaction (UI) None (N)
Scope (S) Unchanged (U)
Confidentiality (C) None (N)
Integrity (I) None (N)
Availability (A) High (H)
NOTE: The below CVSS version 3.0 vector was used to generate this score.
Where can I find a list of all Security Bulletins?
All Security Bulletins are published on our external PSIRT website. Go to http://www.mcafee.com/us/threat-center/product-security-bulletins.aspx and click Security Bulletins - Corporate. Security Bulletins are retired (removed) when a product is both End of Sale and End of Support (End of Life).
How do I report a product vulnerability to McAfee?
If you have information about a security issue or vulnerability with a McAfee product, visit the McAfee PSIRT website for instructions at http://www.mcafee.com/us/threat-center/product-security-bulletins.aspx and click Report a Security Vulnerability.
How does McAfee respond to this and any other reported security flaws?
Our key priority is the security of our customers. If a vulnerability is found within any of our software or services, we work closely with the relevant security software development team to ensure the rapid and effective development of a fix and communication plan.
McAfee publishes Security Bulletins only if they include something actionable such as a workaround, mitigation, version update, or hotfix. Otherwise, we would simply be informing the hacker community that our products are a target, putting our customers at greater risk. For products that are updated automatically, a non-actionable Security Bulletin might be published to acknowledge the discoverer.
View our PSIRT policy on the McAfee PSIRT website at http://www.mcafee.com/us/threat-center/product-security-bulletins.aspx and click About PSIRT.
To contact Technical Support, log on to the ServicePortal and go to the Create a Service Request page at https://support.mcafee.com/ServicePortal/faces/serviceRequests/createSR:
  • If you are a registered user, type your User ID and Password, and then click Log In.
  • If you are not a registered user, click Register and complete the required fields. Your password and logon instructions will be emailed to you.
The information provided in this Security Bulletin is provided as is without warranty of any kind. McAfee disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall McAfee or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if McAfee or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the preceding limitation may not apply.
Any future product release dates mentioned in this Security Bulletin are intended to outline our general product direction, and they should not be relied on in making a purchasing decision. The product release dates are for information purposes only, and may not be incorporated into any contract. The product release dates are not a commitment, promise, or legal obligation to deliver any material, code, or functionality. The development, release, and timing of any features or functionality described for our products remains at our sole discretion and may be changed or canceled at any time.

Rate this document

Beta Translate with

Select a desired language below to translate this page.

Glossary of Technical Terms

 Highlight Glossary Terms

Please take a moment to browse our Glossary of Technical Terms.