www.cisa.gov Open in urlscan Pro
2600:1408:c400:393::447a  Public Scan

Form analysis
2 forms found in the DOM

<form class="gsc-search-box gsc-search-box-tools" accept-charset="utf-8">
  <table cellspacing="0" cellpadding="0" role="presentation" class="gsc-search-box">
    <tbody>
      <tr>
        <td class="gsc-input">
          <div class="gsc-input-box" id="gsc-iw-id1">
            <table cellspacing="0" cellpadding="0" role="presentation" id="gs_id50" class="gstl_50 gsc-input" style="width: 100%; padding: 0px;">
              <tbody>
                <tr>
                  <td id="gs_tti50" class="gsib_a"><input autocomplete="off" type="text" size="10" class="gsc-input" name="search" title="search" aria-label="search" id="gsc-i-id1" dir="ltr" spellcheck="false"
                      style="width: 100%; padding: 0px; border: none; margin: 0px; height: auto; outline: none;"></td>
                  <td class="gsib_b">
                    <div class="gsst_b" id="gs_st50" dir="ltr"><a class="gsst_a" href="javascript:void(0)" title="Clear search box" role="button" style="display: none;"><span class="gscb_a" id="gs_cb50" aria-hidden="true">×</span></a></div>
                  </td>
                </tr>
              </tbody>
            </table>
          </div>
        </td>
        <td class="gsc-search-button"><button class="gsc-search-button gsc-search-button-v2"><svg width="13" height="13" viewBox="0 0 13 13">
              <title>search</title>
              <path
                d="m4.8495 7.8226c0.82666 0 1.5262-0.29146 2.0985-0.87438 0.57232-0.58292 0.86378-1.2877 0.87438-2.1144 0.010599-0.82666-0.28086-1.5262-0.87438-2.0985-0.59352-0.57232-1.293-0.86378-2.0985-0.87438-0.8055-0.010599-1.5103 0.28086-2.1144 0.87438-0.60414 0.59352-0.8956 1.293-0.87438 2.0985 0.021197 0.8055 0.31266 1.5103 0.87438 2.1144 0.56172 0.60414 1.2665 0.8956 2.1144 0.87438zm4.4695 0.2115 3.681 3.6819-1.259 1.284-3.6817-3.7 0.0019784-0.69479-0.090043-0.098846c-0.87973 0.76087-1.92 1.1413-3.1207 1.1413-1.3553 0-2.5025-0.46363-3.4417-1.3909s-1.4088-2.0686-1.4088-3.4239c0-1.3553 0.4696-2.4966 1.4088-3.4239 0.9392-0.92727 2.0864-1.3969 3.4417-1.4088 1.3553-0.011889 2.4906 0.45771 3.406 1.4088 0.9154 0.95107 1.379 2.0924 1.3909 3.4239 0 1.2126-0.38043 2.2588-1.1413 3.1385l0.098834 0.090049z">
              </path>
            </svg></button></td>
        <td class="gsc-clear-button">
          <div class="gsc-clear-button" title="clear results">&nbsp;</div>
        </td>
      </tr>
    </tbody>
  </table>
</form>

<form class="gsc-search-box gsc-search-box-tools" accept-charset="utf-8">
  <table cellspacing="0" cellpadding="0" role="presentation" class="gsc-search-box">
    <tbody>
      <tr>
        <td class="gsc-input">
          <div class="gsc-input-box" id="gsc-iw-id2">
            <table cellspacing="0" cellpadding="0" role="presentation" id="gs_id51" class="gstl_51 gsc-input" style="width: 100%; padding: 0px;">
              <tbody>
                <tr>
                  <td id="gs_tti51" class="gsib_a"><input autocomplete="off" type="text" size="10" class="gsc-input" name="search" title="search" aria-label="search" id="gsc-i-id2" dir="ltr" spellcheck="false"
                      style="width: 100%; padding: 0px; border: none; margin: 0px; height: auto; outline: none;"></td>
                  <td class="gsib_b">
                    <div class="gsst_b" id="gs_st51" dir="ltr"><a class="gsst_a" href="javascript:void(0)" title="Clear search box" role="button" style="display: none;"><span class="gscb_a" id="gs_cb51" aria-hidden="true">×</span></a></div>
                  </td>
                </tr>
              </tbody>
            </table>
          </div>
        </td>
        <td class="gsc-search-button"><button class="gsc-search-button gsc-search-button-v2"><svg width="13" height="13" viewBox="0 0 13 13">
              <title>search</title>
              <path
                d="m4.8495 7.8226c0.82666 0 1.5262-0.29146 2.0985-0.87438 0.57232-0.58292 0.86378-1.2877 0.87438-2.1144 0.010599-0.82666-0.28086-1.5262-0.87438-2.0985-0.59352-0.57232-1.293-0.86378-2.0985-0.87438-0.8055-0.010599-1.5103 0.28086-2.1144 0.87438-0.60414 0.59352-0.8956 1.293-0.87438 2.0985 0.021197 0.8055 0.31266 1.5103 0.87438 2.1144 0.56172 0.60414 1.2665 0.8956 2.1144 0.87438zm4.4695 0.2115 3.681 3.6819-1.259 1.284-3.6817-3.7 0.0019784-0.69479-0.090043-0.098846c-0.87973 0.76087-1.92 1.1413-3.1207 1.1413-1.3553 0-2.5025-0.46363-3.4417-1.3909s-1.4088-2.0686-1.4088-3.4239c0-1.3553 0.4696-2.4966 1.4088-3.4239 0.9392-0.92727 2.0864-1.3969 3.4417-1.4088 1.3553-0.011889 2.4906 0.45771 3.406 1.4088 0.9154 0.95107 1.379 2.0924 1.3909 3.4239 0 1.2126-0.38043 2.2588-1.1413 3.1385l0.098834 0.090049z">
              </path>
            </svg></button></td>
        <td class="gsc-clear-button">
          <div class="gsc-clear-button" title="clear results">&nbsp;</div>
        </td>
      </tr>
    </tbody>
  </table>
</form>

Text Content

Skip to main content

An official website of the United States government

Here’s how you know

Here’s how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United
States.

Secure .gov websites use HTTPS
A lock (LockA locked padlock) or https:// means you’ve safely connected to the
.gov website. Share sensitive information only on official, secure websites.


Cybersecurity & Infrastructure Security Agency
America's Cyber Defense Agency

Search

×

search
 

Menu
Close
×

search
 

 * Topics
   Topics
   Cybersecurity Best Practices
   Cyber Threats and Advisories
   Critical Infrastructure Security and Resilience
   Election Security
   Emergency Communications
   Industrial Control Systems
   Information and Communications Technology Supply Chain Security
   Partnerships and Collaboration
   Physical Security
   Risk Management
   How can we help?
   GovernmentEducational InstitutionsIndustryState, Local, Tribal, and
   TerritorialIndividuals and FamiliesSmall and Medium BusinessesFind Help
   LocallyFaith-Based CommunityExecutives
 * Spotlight
 * Resources & Tools
   Resources & Tools
   All Resources & Tools
   Services
   Programs
   Resources
   Training
   Groups
 * News & Events
   News & Events
   News
   Events
   Cybersecurity Alerts & Advisories
   Directives
   Request a CISA Speaker
   Congressional Testimony
 * Careers
   Careers
   Benefits & Perks
   HireVue Applicant Reasonable Accommodations Process
   Hiring
   Resume & Application Tips
   Students & Recent Graduates
   Veteran and Military Spouses
   Work @ CISA
 * About
   About
   Culture
   Divisions & Offices
   Regions
   Leadership
   Doing Business with CISA
   Site Links
   Reporting Employee and Contractor Misconduct
   CISA GitHub
   Contact Us

Report a Cyber Issue
America's Cyber Defense Agency
Breadcrumb
 1. Home
 2. News & Events
 3. Cybersecurity Advisories
 4. Alert

Share:


Alert


SIDE-CHANNEL VULNERABILITY VARIANTS 3A AND 4

Last Revised
May 22, 2018
Alert Code
TA18-141A



SYSTEMS AFFECTED

CPU hardware implementations


OVERVIEW

On May 21, 2018, new variants of the side-channel central processing unit (CPU)
hardware vulnerabilities known as Spectre and Meltdown were publicly
disclosed(link is external). These variants—known as 3A and 4—can allow an
attacker to obtain access to sensitive information on affected systems.

Common CPU hardware implementations are vulnerable to the side-channel attacks
known as Spectre and Meltdown. Meltdown is a bug that "melts" the security
boundaries normally enforced by the hardware, affecting desktops, laptops, and
cloud computers. Spectre is a flaw that an attacker can exploit to force a CPU
to reveal its data.

Variant 3a is a vulnerability that may allow an attacker with local access to
speculatively read system parameters via side-channel analysis and obtain
sensitive information.

Variant 4 is a vulnerability that exploits “speculative bypass.” When exploited,
Variant 4 could allow an attacker to read older memory values in a CPU’s stack
or other memory locations. While implementation is complex, this side-channel
vulnerability could allow less privileged code to

 * Read arbitrary privileged data; and
 * Run older commands speculatively, resulting in cache allocations that could
   be used to exfiltrate data by standard side-channel methods.

Corresponding CVEs for Side-Channel Variants 1, 2, 3, 3a, and 4 are found below:

 * Variant 1: Bounds Check Bypass – CVE-2017-5753
 * Variant 2: Branch Target Injection – CVE-2017-5715
 * Variant 3: Rogue Data Cache Load – CVE-2017-5754
 * Variant 3a: Rogue System Register Read – CVE-2018-3640  
 * Variant 4: Speculative Store Bypass – CVE-2018-3639


IMPACT

Side-Channel Vulnerability Variants 3a and 4 may allow an attacker to obtain
access to sensitive information on affected systems.


SOLUTION


MITIGATION

NCCIC recommends users and administrators

 * Refer to their hardware and software vendors for patches or microcode,
 * Use a test environment to verify each patch before implementing, and
 * Ensure that performance is monitored for critical applications and services.
   * Consult with vendors and service providers to mitigate any degradation
     effects, if possible.
   * Consult with Cloud Service Providers to mitigate and resolve any impacts
     resulting from host operating system patching and mandatory rebooting, if
     applicable.

The following table contains links to advisories and patches published in
response to the vulnerabilities. This table will be updated as information
becomes available.



Link to Vendor Information Date Added AMD(link is external) May 21, 2018
ARM(link is external) May 21, 2018 Intel(link is external) May 22, 2018
Microsoft(link is external) May 21, 2018 Redhat(link is external) May 21, 2018


REFERENCES

Google Project Zero Blog(link is external)
Bounds Check Bypass – CVE-2017-5753(link is external)
Branch Target Injection – CVE-2017-5715(link is external)
Rogue Data Cache Load – CVE-2017-5754(link is external)
Rogue System Register Read – CVE-2018-3640 (link is external)
Speculative Store Bypass – CVE-2018-3639(link is external)
TA18-004A – Meltdown and Spectre Side-Channel Vulnerability Guidance


REVISIONS

May 21, 2018: Initial version|May 22, 2018: Added information and link to Intel
in table

This product is provided subject to this Notification and this Privacy &
Use policy.


PLEASE SHARE YOUR THOUGHTS

We recently updated our anonymous product survey; we’d welcome your feedback.


RELATED ADVISORIES

Oct 19, 2023
Alert


CISA, NSA, FBI, AND MS-ISAC RELEASE UPDATE TO #STOPRANSOMWARE GUIDE

Oct 19, 2023
Alert


CISA ADDS TWO KNOWN EXPLOITED VULNERABILITIES TO CATALOG

Oct 19, 2023
Alert


CISA RELEASES ONE INDUSTRIAL CONTROL SYSTEMS ADVISORY

Oct 19, 2023
Alert


ORACLE RELEASES OCTOBER 2023 CRITICAL PATCH UPDATE ADVISORY

Return to top
 * Topics
 * Spotlight
 * Resources & Tools
 * News & Events
 * Careers
 * About

Cybersecurity & Infrastructure Security Agency
 * Facebook
 * Twitter
 * LinkedIn
 * YouTube
 * Instagram
 * RSS

CISA Central 888-282-0870 Central@cisa.dhs.gov(link sends email)
DHS Seal
CISA.gov
An official website of the U.S. Department of Homeland Security
 * About CISA
 * Accessibility
 * Budget and Performance
 * DHS.gov
 * FOIA Requests
 * No FEAR Act
 * Office of Inspector General
 * Privacy Policy
 * Subscribe
 * The White House
 * USA.gov
 * Website Feedback