Security readout for executives and security teams
Plain-English summary
This flaw lets a local, already-authenticated attacker turn limited access on an affected Advantech DeviceOn/iService 1.1.7 system into NT SYSTEM privileges. That means the attacker could gain near-total control of that host. The source bundle does not show active exploitation or a confirmed fixed version.
Executive priority
Treat this as high priority for any environment using DeviceOn/iService 1.1.7, especially where shared access, remote administration, or prior compromise is plausible. It is not described as remotely exploitable from the network.
Technical view
CVE-2021-40396 is a local privilege escalation in the Advantech DeviceOn/iService 1.1.7 installation. The CVSS 3.0 score is 8.8 with low attack complexity, low privileges required, no user interaction, and high confidentiality, integrity, and availability impact. The mapped weakness is CWE-276, incorrect default permissions.
Likely exposure
Exposure is likely limited to systems where Advantech DeviceOn/iService 1.1.7 is installed and a low-privileged attacker can access the host locally or through an existing foothold.
Exploitation context
The CVE is not listed as KEV in the provided bundle, and no cited source in the bundle states active exploitation. The vulnerability requires local access and low privileges, then abuses replaceable files to escalate to NT SYSTEM.
Researcher notes
The provided record names DeviceOn/iService 1.1.7 despite generic affected fields. Patch status and detailed vendor remediation are not included in the source bundle, so validation should avoid assuming a fixed release without checking vendor guidance.
Mitigation direction
- Identify all hosts running Advantech DeviceOn/iService 1.1.7.
- Check Advantech and Talos guidance for fixed versions or supported workarounds.
- Restrict local user access to systems running the affected installation.
- Review and harden writable permissions on application installation files after vendor validation.
- Prioritize endpoint monitoring for unexpected file replacement in the product path.
Validation and detection
- Verify installed DeviceOn/iService versions across managed assets.
- Confirm whether any affected host permits low-privileged local users.
- Review product installation file permissions for unsafe write access.
- Check endpoint logs for suspicious file replacement or privilege changes.
- Document whether vendor-fixed software or compensating controls are applied.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-276: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupPrivilege behavior lookup
The CVE wording references privilege impact, so privilege escalation and authorization behavior review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-40396 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.8 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H26Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
8.8HighVector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://talosintelligence.com/vulnerability_reports/TALOS-2021-1408CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Incorrect Default Permissions
Incorrect Default Permissions represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.