CVE-2020-13555

NT SYSTEM escalation via writable COM server files

Published Feb 17, 2021 · Updated Aug 4, 2024

Incorrect default permissions on COM server files in Advantech WebAccess/SCADA 9.0.1 allow local users to execute code as NT SYSTEM. ACLs on ACProjDecrypt.dll and other COM server binaries grant Authenticated Users change access, permitting replacement before privileged loading. A low-privileged Windows account must alter a referenced binary and wait for a higher-privileged COM client to invoke it.

CVSS severity8.8
High
EPSS probability0.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect default permissions on COM server files in Advantech WebAccess/SCADA 9.0.1 allow local users to execute code as NT SYSTEM. ACLs on ACProjDecrypt.dll and other COM server binaries grant Authenticated Users change access, permitting replacement before privileged loading. A low-privileged Windows account must alter a referenced binary and wait for a higher-privileged COM client to invoke it.

The record

CVE
CVE-2020-13555
Published
Feb 17, 2021
Updated
Aug 4, 2024
Vendor
Advantech
Product
WebAccess/SCADA
Classifications
CWE-276, T1574.001
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 17, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Advantech WebAccess/SCADA 9.0.1

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Advantech · WebAccess/SCADAversion=Advantech WebAccess/SCADA 9.0.1

Published CVSS scores

8.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
8.8Cisco TalosCVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
7.2NIST NVDAV:L/AC:L/Au:N/C:C/I:C/A:C

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-276Incorrect Default Permissions
T1574.001Hijack Execution Flow: DLL

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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