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OssecApplication

CVE-2020-8445

CRITICAL · 9.8 CVSS v3.1 Published 2020-01-30
Fix available
A fix is available. Upgrade to after 3.5.0 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In OSSEC-HIDS 2.7 through 3.5.0, the OS_CleanMSG function in ossec-analysisd doesn't remove or encode terminal control characters or newlines from processed log messages. In many cases, those characters are later logged. Because newlines (\n) are permitted in messages processed by ossec-analysisd, it may be possible to inject nested events into the ossec log. Use of terminal control characters may allow obfuscating events or executing commands when viewed through vulnerable terminal emulators. This may be an unauthenticated remote attack for certain types and origins of logged data.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

In OSSEC-HIDS 2.7-3.5.0, the OS_CleanMSG function in ossec-analysisd fails to remove or encode terminal control characters and newlines from processed log messages, allowing injection of nested events into logs and potential command execution via terminal emulator vulnerabilities when those characters are displayed.

MitigationUpgrade OSSEC-HIDS beyond version 3.5.0 to obtain the patched version, or implement input sanitization in the OS_CleanMSG function to strip or properly encode terminal control characters and newlines before logging.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
OssecApplication
Affected:>= 2.7, <= 3.5.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check if OSSEC-HIDS is installed
    Run 'which ossec-analysisd' or look for OSSEC directories such as /var/ossec or /opt/ossec
    Affected if OSSEC-HIDS is found on the system
  2. Determine the installed OSSEC version
    Run 'ossec-analysisd -V' or check /var/ossec/etc/ossec.conf for version information, or examine the output of 'agent_control -l' if available
    Affected if The version is 2.7 or higher, up to and including 3.5.0
  3. Verify ossec-analysisd component is active
    Check if the ossec-analysisd process is running using 'ps aux | grep analysisd' or check service status
    Affected if The ossec-analysisd process is running and processing logs
  4. Confirm logs are being processed through OS_CleanMSG
    Review OSSEC configuration files (local_rules.xml, etc.) to confirm event analysis is enabled and examine whether log messages are being written to alerts.log or similar output files
    Affected if OSSEC is actively analyzing and logging events

You are affected if OSSEC-HIDS versions 2.7 through 3.5.0 are installed with ossec-analysisd running and processing log messages through the vulnerable OS_CleanMSG function.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 3.5.0
Interim mitigation

Upgrade OSSEC-HIDS beyond version 3.5.0 to obtain the patched version, or implement input sanitization in the OS_CleanMSG function to strip or properly encode terminal control characters and newlines before logging.

Recommended fix Moderate confidence

OSSEC-HIDS 3.6.0 or later

  1. 1. Identify the current OSSEC-HIDS version by running 'ossec-control -V' or checking the installed package
  2. 2. Backup the OSSEC configuration directory (typically /var/ossec or /etc/ossec) before upgrading
  3. 3. Download OSSEC version 3.6.0 or later from the official GitHub repository (github.com/ossec/ossec-hids)
  4. 4. Stop the OSSEC service using 'ossec-control stop'
  5. 5. Install the new version using the standard installation process (./install.sh or the appropriate package manager for your distribution)
  6. 6. Verify the upgrade was successful by checking the version with 'ossec-control -V'
  7. 7. Start the OSSEC service using 'ossec-control start'
  8. 8. Monitor the ossec.log file to ensure the system is processing logs correctly without terminal control character issues
Caveat Minor - Upgrading between minor versions (3.x) typically retains configuration compatibility, but test in a staging environment first

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Ossec Scoped from the published advisory
  • Consultation4.0 h
  • Implementation12.0 h
  • Testing8.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,880
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2020-8445 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data