Security Resilience

CVE-2023-28806

Zscaler Client Connector ≤ 4.2.0.190

Published
06 August 2024
Modified
07 August 2024
Patch / advisory
View advisory
CVSS Score v3.1 5.7
Click a component to see what it means
Raw vectorCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N
EPSS Score 0.0019 8th percentile
Risk Priority 41 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2023-28806 is a medium-severity Improper Verification of Cryptographic Signature (CWE-347) vulnerability in Zscaler Client Connector. Its CVSS base score is 5.7 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Junk Data (T1001.001); ranked at the 8th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SC-13 (Cryptographic Protection) and SI-7 (Software, Firmware, and Information Integrity) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A04:2025 Cryptographic Failures

EU & UK References

Vulnerability Data

An Improper Validation of signature in Zscaler Client Connector on Windows allows an authenticated user to disable anti-tampering. This issue affects Client Connector on Windows <4.2.0.190.

CWE(s)
CWE-347

Related Threats

MITRE ATT&CK Enterprise Techniques

T1001.001 Junk Data Command And Control
Adversaries may add junk data to protocols used for command and control to make detection more difficult.
attack.mitre.org →
T1001.002 Steganography Command And Control
Adversaries may use steganographic techniques to hide command and control traffic to make detection efforts more difficult.
attack.mitre.org →
T1003.005 Cached Domain Credentials Credential Access
Adversaries may attempt to access cached domain credentials used to allow authentication to occur in the event a domain controller is unavailable.
attack.mitre.org →
T1003.006 DCSync Credential Access
Adversaries may attempt to access credentials and other sensitive information by abusing a Windows Domain Controller's application programming interface (API)(Citation: Microsoft DRSR Dec 2017) (Citation: Microsoft GetNCCChanges) (Citati…
attack.mitre.org →
T1003.007 Proc Filesystem Credential Access
Adversaries may gather credentials from the proc filesystem or `/proc`.
attack.mitre.org →
T1012 Query Registry Discovery
Adversaries may interact with the Windows Registry to gather information about the system, configuration, and installed software.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2024-23460Same product: Zscaler Client Connector
CVE-2023-28804Same product: Zscaler Client Connector
CVE-2024-23456Same product: Zscaler Client Connector
CVE-2024-23480Same product: Zscaler Client Connector
CVE-2023-28796Same product: Zscaler Client Connector
CVE-2023-28802Same product: Zscaler Client Connector
CVE-2024-23462Same product: Zscaler Client Connector
CVE-2024-23461Same product: Zscaler Client Connector
CVE-2023-41970Same product: Zscaler Client Connector
CVE-2023-28803Same product: Zscaler Client Connector

Affected Assets

zscaler
client connector
≤ 4.2.0.190

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 14 hardening rules · 5 OS baselines
Validate
Prove the fix (OWASP ASVS)

—

Mitigating Controls (NIST 800-53 r5) AI

SC-13 Cryptographic Protection good match

Requiring cryptographic protection mechanisms forces correct signature verification to be implemented for data protection.

SI-7 Software, Firmware, and Information Integrity good match

Mandating integrity verification tools directly requires proper cryptographic signature checking to detect unauthorized changes.

SC-23 Session Authenticity partial match

Protecting session authenticity requires correct verification of cryptographic signatures or equivalent mechanisms.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

ID.RA-09 partial match
blocks

Requires assessing authenticity and integrity of acquired assets, which commonly relies on signature verification but is limited to pre-acquisition.

PR.DS-01 partial match
blocks

Digital signatures are explicitly cited to protect integrity of data-at-rest, so proper verification directly mitigates the weakness.

PR.DS-02 partial match
blocks

Digital signatures are explicitly cited to protect integrity of data-in-transit, so proper verification directly mitigates the weakness.

PR.PS-06 partial match
blocks

Secure SDLC practices include code signing and signature verification requirements, addressing the weakness during development.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.5.14 Information transfer partial match
removes
A.5.15 Access control partial match
removes
A.5.16 Identity management partial match
removes
A.5.17 Authentication information partial match
removes
A.5.18 Access rights partial match
removes
A.8.10 Information deletion partial match
removes

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (higher-evidence rows only; rows rated `none` are excluded).

Oracle Linux 8 (2 rules)
  • V-248574 YUM must be configured to prevent the installation of patches, service packs, device drivers, or OL 8 system components that have not been digitally signed using a certificate that is recognized and approved by the organization. blocks CWE-347
  • V-248575 OL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. blocks CWE-347
Oracle Linux 9 (2 rules)
  • V-271525 OL 9 must have GPG signature verification enabled for all software repositories. blocks CWE-347
  • V-271523 OL 9 must check the GPG signature of locally installed software packages before installation. blocks CWE-347
RHEL 7 (2 rules)
  • V-204447 The Red Hat Enterprise Linux operating system must prevent the installation of software, patches, service packs, device drivers, or operating system components from a repository without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. blocks CWE-347
  • V-204448 The Red Hat Enterprise Linux operating system must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. blocks CWE-347
RHEL 8 (1 rule)
  • V-230264 RHEL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components from a repository without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. blocks CWE-347
RHEL 9 (1 rule)
  • V-257822 RHEL 9 must have GPG signature verification enabled for all software repositories. blocks CWE-347

References