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Umbrella Virtual ApplianceApplication · Cisco

CVE-2017-6679

MEDIUM · 6.4 CVSS v3.1 Published 2017-12-01
Fix available
A fix is available. Upgrade to 2.1.0 or later.
See remediation →
66/100
Remediation priority · Elevated
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
The Cisco Umbrella Virtual Appliance Version 2.0.3 and prior contained an undocumented encrypted remote support tunnel (SSH) which auto initiated from the customer's appliance to Cisco's SSH Hubs in the Umbrella datacenters. These tunnels were primarily leveraged for remote support and allowed for authorized/authenticated personnel from the Cisco Umbrella team to access the appliance remotely and obtain full control without explicit customer approval. To address this vulnerability, the Umbrella Virtual Appliance version 2.1.0 now requires explicit customer approval before an SSH tunnel from the VA to the Cisco terminating server can be established.

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

The Cisco Umbrella Virtual Appliance versions 2.0.3 and prior contained an undocumented auto-initiated SSH tunnel that connected from customer VA instances to Cisco Umbrella datacenter SSH hubs without customer knowledge or consent, allowing Cisco support personnel remote access and full control of the appliance.

MitigationUpgrade to Cisco Umbrella Virtual Appliance version 2.1.0 or later, which implements explicit customer approval before the SSH tunnel can be established to Cisco infrastructure.

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
Umbrella Virtual ApplianceApplication
Affected:< 2.1.0

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
Local
Complexity
High
Privileges
High
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:H/PR:H/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. Identify the installed Cisco Umbrella Virtual Appliance version
    Access the VA management interface or run the command to display the appliance version (typically via admin console or CLI command such as 'show version' or 'version' depending on the appliance OS)
    Affected if The displayed version is 2.0.3 or any version prior to 2.1.0
  2. Examine active SSH connections originating from the appliance
    Use netstat or ss commands to list established outbound SSH connections (e.g., 'netstat -antp | grep ESTABLISHED' or 'ss -tnp | grep ESTABLISHED'), noting remote IP addresses and ports
    Affected if Outbound SSH connections are present to IP addresses belonging to Cisco Umbrella datacenter infrastructure without documented customer configuration
  3. Review SSH client configuration for tunnel settings
    Inspect the SSH configuration files in the appliance, typically located in /etc/ssh/ or the home directory of the service account, looking for Host entries or ProxyJump/ProxyCommand directives pointing to Cisco infrastructure
    Affected if SSH configuration contains undocumented tunnel definitions connecting to Cisco Umbrella infrastructure
  4. Check for auto-initiated SSH tunnel processes
    List running processes related to SSH (ps aux | grep ssh) and examine if any SSH client processes are running with tunnel or port-forwarding flags (-L, -R, -N) pointing to external Cisco destinations
    Affected if SSH processes with tunnel flags are running automatically without explicit customer configuration

The environment is affected if the Cisco Umbrella Virtual Appliance version is below 2.1.0 and an undocumented auto-initiated SSH tunnel to Cisco infrastructure is present or configured.

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.

From vendor data
Upgrade available Upgrade to 2.1.0 or later
Fixed in 2.1.0
Interim mitigation

Upgrade to Cisco Umbrella Virtual Appliance version 2.1.0 or later, which implements explicit customer approval before the SSH tunnel can be established to Cisco infrastructure.

Fix this in Umbrella Virtual Appliance Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.

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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-2017-6679 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