CriticalCVE-2019-1069

Task Scheduler Elevation of Privilege Vulnerability (CVE-2019-1069)

Published 12.06.2019In CISA KEV since 15.03.2022Sources: CVE.org

What is affected, what to do

The vulnerability is being actively exploited; treat it as a priority. CISA lists it as used in ransomware campaigns. The available sources name no fixed version. Check the vendor guidance in the references below. Immediate actions, mitigation and detection rules are in the runbook below.

Affected: Microsoft Windows 10 Version 1703 gte 10.0.0..*
Microsoft Windows 10 Version 1803 gte 10.0.0..*
Microsoft Windows Server, version 1803 (Server Core Installation) gte 10.0.0..*
Microsoft Windows 10 Version 1809 gte 10.0.17763.0..*
Microsoft Windows 10 Version 1809 gte 10.0.0..*
Microsoft Windows Server 2019 gte 10.0.17763.0..*
Microsoft Windows Server 2019 (Server Core installation) gte 10.0.17763.0..*
Microsoft Windows 10 Version 1709 for 32-bit Systems gte 10.0.0..*
Microsoft Windows 10 Version 1709 gte 10.0.0..*
Microsoft Windows 10 Version 1903 for 32-bit Systems gte 10.0.0..*
Microsoft Windows 10 Version 1903 for x64-based Systems gte 10.0.0..*
Microsoft Windows 10 Version 1903 for ARM64-based Systems gte 10.0.0..*
Microsoft Windows Server, version 1903 (Server Core installation) gte 10.0.0..*
Microsoft Windows 10 Version 1507 gte 10.0.10240.0..*
Microsoft Windows 10 Version 1607 gte 10.0.14393.0..*
Microsoft Windows Server 2016 gte 10.0.14393.0..*
Microsoft Windows Server 2016 (Server Core installation) gte 10.0.14393.0..*

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Metrics

7.8

Priority

XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

Source: NVD, CVSS v3

7.8

CVSS v3

Severity High on the scale from 0 to 10.

Source: CVE.org

6.2 %

EPSS score

Moderate — model estimates 1-10% exploitation likelihood.

Source: FIRST EPSS, percentile 93.5

Show all metrics

Severity: Critical
Priority (0–325) The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first? Read in glossary: 233.95 Methodology
Exploit maturity An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack. Read in glossary: actively exploited
XIEM Effective CVSS XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command. Read in glossary: 7.8 Methodology
CVSS v3 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 7.8
EPSS score The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“. Read in glossary: 6.2 %; Moderate — model estimates 1-10% exploitation likelihood.
EPSS percentile The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking. Read in glossary: 93.5; Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
KEV status The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching. Read in glossary: Actively exploited
Published: 12.06.2019
In CISA KEV since The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching. Read in glossary: 15.03.2022
CISA assessment (SSVC): Exploitation: active · not automatable · Technical impact: total; Source: CISA Vulnrichment, as of 14 March 2022
CWE CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect. Read in glossary: CWE-59

Response and mitigation

Why act now?

Prioritisation rationale

This is a reliable, low-complexity local privilege escalation with a public exploit available since 2019. Attackers use it as the second stage after initial access via phishing, compromised RDP accounts or a webshell. CISA flags it as used in ransomware campaigns, which confirms its role in the chain from user context to SYSTEM and on to domain compromise. Exploitation likelihood is high for a local-only bug. If your estate has no legacy Windows builds, regular patching has effectively closed this risk. Any remaining Windows 10 1903-or-older or Server 1803 host, however, is a critical hygiene gap that NIS2 vulnerability-handling obligations (Art. 21) require you to remediate or isolate immediately.

01
Runbook step 1
Immediate response (0-24 h)
- Apply the security update: Microsoft fixed this in the June 2019 Patch Tuesday cumulative update. Look up the KB number for each build in the MSRC advisory for CVE-2019-1069. Use WSUS/Intune/SCCM to confirm that every Windows 10 1507–1903 and Windows Server 1803 host is at or above that patch level.
- Hunt down out-of-support builds: Every affected build is end-of-life. Any host still running one of these versions is a hygiene failure and should be upgraded to a supported Windows release or isolated as a priority. Filter the asset inventory by build, e.g. DeviceInfo | where OSVersion in ("1507","1607","1703","1709","1803","1809","1903").
- Patch multi-user systems first: Prioritise RDS/terminal servers, VDI pools, jump hosts and kiosks. On these systems many unprivileged accounts can run code, and a local EoP gives direct SYSTEM.
- Assume escalation on compromised unpatched hosts: If there is any sign of unauthorised code execution (phishing payload, webshell, loader), assume the attacker has escalated. Isolate the host, rotate the local admin password (LAPS) and treat cached domain credentials as exposed.
- Verify ACL integrity: On suspect hosts, use icacls to compare the DACLs of critical files under C:\Windows\System32 against a known-good baseline. The known exploit uses hardlinks to rewrite permissions on arbitrary system files.
02
Runbook step 2
Mitigation layers
- Application control (endpoint hardening): Enforce WDAC or AppLocker. Standard users should only run signed, approved binaries, and execution from %TEMP%, %APPDATA%, Downloads and C:\Users\Public should be blocked. The public PoC is typically dropped and run as a standalone EXE from user-writable paths.
- Restrict legacy task interfaces: The exploit abuses the import of legacy .job files from C:\Windows\Tasks via schtasks.exe /change. Block schtasks.exe for non-admins with an AppLocker rule. Only tighten write permissions on C:\Windows\Tasks after testing in a pilot group, because some legacy software still uses that path.
- Least privilege (IAM): Remove local admin rights, roll out LAPS or Windows LAPS, and apply tiering according to the Microsoft Enterprise Access Model. The goal is that SYSTEM on a workstation yields no Domain Admin credentials in memory, so enable Credential Guard.
- Defender ASR rules: Enable "Block credential stealing from LSASS" and the prevalence/age/trusted-list executable rule. These raise the cost of post-escalation activity.
- Network segmentation: Move hosts that cannot be patched into a dedicated VLAN. Allow egress only via proxy and block SMB/RDP/WinRM from that segment into server and admin networks. This contains lateral movement after local escalation.
03
Runbook step 3
Detection rules
- Sysmon EID 11 (FileCreate): A *.job file is created under C:\Windows\Tasks\ by a non-SYSTEM, non-admin process. Sigma shape: TargetFilename|startswith: 'C:\Windows\Tasks\' AND TargetFilename|endswith: '.job' AND User|not: 'NT AUTHORITY\SYSTEM'.
- Sysmon EID 1 / Security 4688: schtasks.exe runs with /change or /create at medium integrity, especially when the parent is an unknown binary in a user path. KQL: DeviceProcessEvents | where FileName =~ "schtasks.exe" and ProcessCommandLine has "/change" and ProcessIntegrityLevel == "Medium".
- Security 4670 / 4663 (SACL required): Permission changes on files under C:\Windows\System32 or on service/driver binaries are performed by the Schedule service's svchost.exe right after a .job file appears. Set WRITE_DAC auditing on a curated set of system files.
- EDR process chain: An unprivileged process creates NTFS hardlinks (CreateHardLink/NtSetInformationFile with FileLinkInformation) pointing into System32. Shortly afterwards, a SYSTEM process starts whose binary or DLL was recently modified. Correlate in MDE: DeviceFileEvents followed by DeviceProcessEvents where AccountSid == "S-1-5-18".
- Security 4698/4702: Scheduled tasks are created or modified by standard users outside software deployment windows. Correlate these events with ransomware precursors such as vssadmin delete shadows, wbadmin or Defender tampering.

Detection rules

No NEOSEC detection rule is available for this vulnerability yet.

Classification under NIS2 and CRA

Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

NIS2 NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management. Read in glossary: Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
CRA The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates. Read in glossary: Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
ISO/IEC 27001 ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security. Read in glossary: Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

Description

An elevation of privilege vulnerability exists in the way the Task Scheduler Service validates certain file operations. An attacker who successfully exploited the vulnerability could gain elevated privileges on a victim system. To exploit the vulnerability, an attacker would require unprivileged code execution on a victim system. The security update addresses the vulnerability by correctly validating file operations.

Source: CISA KEV Catalog, cvelistv5, NVD (NIST)

Affected products

The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

Affected products
		Affected versions	Fixed in
Microsoft	Windows 10 Version 1507	`≥ 10.0.10240.0`	—
Microsoft	Windows 10 Version 1607	`≥ 10.0.14393.0`	—
Microsoft	Windows 10 Version 1703	`≥ 10.0.0`	—
Microsoft	Windows 10 Version 1709	`≥ 10.0.0`	—
Microsoft	Windows 10 Version 1709 for 32-bit Systems	`≥ 10.0.0`	—
Microsoft	Windows 10 Version 1803	`≥ 10.0.0`	—
Microsoft	Windows 10 Version 1809	`≥ 10.0.0` `≥ 10.0.17763.0`	— —
Microsoft	Windows 10 Version 1903 for 32-bit Systems	`≥ 10.0.0`	—
Microsoft	Windows 10 Version 1903 for ARM64-based Systems	`≥ 10.0.0`	—
Microsoft	Windows 10 Version 1903 for x64-based Systems	`≥ 10.0.0`	—
Microsoft	Windows Server 2016	`≥ 10.0.14393.0`	—
Microsoft	Windows Server 2016 (Server Core installation)	`≥ 10.0.14393.0`	—
Microsoft	Windows Server 2019	`≥ 10.0.17763.0`	—
Microsoft	Windows Server 2019 (Server Core installation)	`≥ 10.0.17763.0`	—
Microsoft	Windows Server, version 1803 (Server Core Installation)	`≥ 10.0.0`	—
Microsoft	Windows Server, version 1903 (Server Core installation)	`≥ 10.0.0`	—

Vendors and products

Affected operating systems

Affected operating systems

Windows	microsoft	windows_10_1507	—
Windows	microsoft	windows_10_1607	—
Windows	microsoft	windows_10_1703	—
Windows	microsoft	windows_10_1709	—
Windows	microsoft	windows_10_1803	—
Windows	microsoft	windows_10_1809	—
Windows	microsoft	windows_10_1903	—
Windows	microsoft	windows_server_1803	—
Windows	microsoft	windows_server_1903	—
Windows	microsoft	windows_server_2016	—
Windows	microsoft	windows_server_2019	—

Weakness classes (CWE)

CWE-59Improper Link Resolution Before File Access ('Link Following')
Base
The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.
Entry at MITRE CWE-59

Public exploit references

Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

Public exploit references

CISA KEV Catalog	CISA Known Exploited Vulnerability (opens in a new tab)cisa.gov	actively exploited	15.03.2022

References & sources

Microsoft Security Update GuideTask Scheduler Elevation of Privilege VulnerabilityVendor advisory
kb.cert.orgVU#119704Third-party advisory, x_refsource_CERT-VN, x_transferred
portal.msrc.microsoft.comen-US/security-guidance/advisory/CVE-2019-1069x_refsource_MISC, x_transferred
blog.0patch.com2019/06/another-task-scheduler-0day-another.htmlx_refsource_MISC, x_transferred
cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2019-1069government-resource

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What is affected, what to do

Metrics

Response and mitigation

Prioritisation rationale

Immediate response (0-24 h)

Mitigation layers

Detection rules

Detection rules

Classification under NIS2 and CRA

Description

Affected products

Vendors and products

Affected operating systems

Weakness classes (CWE)

Public exploit references

References & sources