CyberSecBulletin
CVE-2021-20021Exploited in the wildNVD status: Analyzed

SonicWall Email Security Improper Privilege Management

Published Updated By the CyberSecBulletin desk

CVE-2021-20021 is a critical-severity improper privilege management vulnerability in Email Security from SonicWall, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected Email Security versions: 10.0.9 and earlier. The record does not name a fixed version, so check the vendor advisory. CISA added it to the Known Exploited Vulnerabilities catalogue on November 3, 2021, which means attacks have been observed in the wild, including in ransomware campaigns.

Patch now

Attackers are already exploiting this vulnerability, according to CISA.

What to do

  1. Update Email Security Appliance 9000 Firmware to 10.0.9.6105 or a later version.
  2. Update Email Security Appliance 3300 Firmware to 10.0.9.6105 or a later version.
  3. Update Email Security Appliance 4300 Firmware to 10.0.9.6105 or a later version.
  4. CISA's required action: Apply updates per vendor instructions.
  5. Read the advisory on psirt.global.sonicwall.com for workarounds and exact fixed builds.
  6. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
SonicWallEmail Security10.0.9 and earlierNot stated
SonicWallEmail Security Appliance 9000 Firmwarebefore 10.0.9.610510.0.9.6105
SonicWallEmail Security Appliance 3300 Firmwarebefore 10.0.9.610510.0.9.6105
SonicWallEmail Security Appliance 4300 Firmwarebefore 10.0.9.610510.0.9.6105
SonicWallEmail Security Appliance 8300 Firmwarebefore 10.0.9.610510.0.9.6105
SonicWallEmail Security Appliance 5000 Firmwarebefore 10.0.9.610510.0.9.6105
SonicWallEmail Security Appliance 7000 Firmwarebefore 10.0.9.610510.0.9.6105
SonicWallEmail Security Appliance 5050 Firmwarebefore 10.0.9.610510.0.9.6105
SonicWallEmail Security Appliance 7050 Firmwarebefore 10.0.9.610510.0.9.6105
SonicWallEmail Security Virtual Appliancebefore 10.0.9.610510.0.9.6105
SonicWallHosted Email Securitybefore 10.0.9.610310.0.9.6103

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.19.8CriticalNVD
CVSS 3.19.8CriticalCISA (ADP)
CVSS 2.07.5HighNVD

Official description

A vulnerability in the SonicWall Email Security version 10.0.9.x allows an attacker to create an administrative account by sending a crafted HTTP request to the remote host.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Privilege Management

The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.

How developers prevent this class of flaw

  • Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
  • Follow the principle of least privilege when assigning access rights to entities in a software system.
  • Consider following the principle of separation of privilege. Require multiple conditions to be met before permitting access to a system resource.

More Improper Privilege Management vulnerabilities (CWE-269)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: active, automatable: yes, technical impact: total).
  3. Added to CISA's Known Exploited Vulnerabilities catalogue.
  4. Deadline for US federal agencies to remediate, set by CISA.
  5. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Other vulnerabilities in Email Security

All Email Security vulnerabilities

Recent Improper Privilege Management vulnerabilities

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