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JunosOperating system · Juniper

CVE-2015-5361

MEDIUM · 6.5 CVSS v3.1 Published 2020-02-28
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
74/100
Remediation priority · Elevated
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
Background For regular, unencrypted FTP traffic, the FTP ALG can inspect the unencrypted control channel and open related sessions for the FTP data channel. These related sessions (gates) are specific to source and destination IPs and ports of client and server. The design intent of the ftps-extensions option (which is disabled by default) is to provide similar functionality when the SRX secures the FTP/FTPS client. As the control channel is encrypted, the FTP ALG cannot inspect the port specific information and will open a wider TCP data channel (gate) from client IP to server IP on all destination TCP ports. In FTP/FTPS client environments to an enterprise network or the Internet, this is the desired behavior as it allows firewall policy to be written to FTP/FTPS servers on well-known control ports without using a policy with destination IP ANY and destination port ANY. Issue The ftps-extensions option is not intended or recommended where the SRX secures the FTPS server, as the wide data channel session (gate) will allow the FTPS client temporary access to all TCP ports on the FTPS server. The data session is associated to the control channel and will be closed when the control channel session closes. Depending on the configuration of the FTPS server, supporting load-balancer, and SRX inactivity-timeout values, the server/load-balancer and SRX may keep the control channel open for an extended period of time, allowing an FTPS client access for an equal duration.​ Note that the ftps-extensions option is not enabled by default.

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 ftps-extensions option in Juniper SRX firewalls creates a permissive TCP data channel (allowing all destination ports from client to server) when handling encrypted FTPS traffic. When the SRX protects an FTPS server rather than a client, this design flaw grants FTPS clients temporary access to every TCP port on the server for the duration of the control channel session, creating a significant attack surface expansion.

MitigationDisable the ftps-extensions option on SRX devices that secure FTPS servers, as this feature is only intended for FTPS client deployments. Review all SRX policies to identify and remediate any instances where ftps-extensions is enabled on server-facing security zones.

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
JunosOperating system
Affected:= 12.1x44= 12.1x46= 12.1x46-d10= 12.1x47= 12.3x48= 15.1x49

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
Low
Integrity
Low
Availability
None

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

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 Junos version on SRX device
    Run `show version` command on the SRX device to obtain the installed Junos version
    Affected if Version matches any of: 12.1x44, 12.1x46, 12.1x46-d10, 12.1x47, 12.3x48, or 15.1x49
  2. Verify ftps-extensions is configured
    Run `show configuration | match ftps-extensions` or `show configuration security policies` to search for ftps-extensions configuration in security policies
    Affected if The ftps-extensions option is present and enabled in any security policy configuration
  3. Identify server-facing FTPS policies
    Review all security policies containing ftps-extensions and identify whether they protect FTPS servers (server-facing) or FTPS clients (client-facing) by examining source/destination zones and addresses
    Affected if A policy with ftps-extensions is applied to protect an FTPS server (inbound traffic to a server behind the SRX)
  4. Check policy action and destination ports
    Examine the full policy configuration: `show configuration security policies from-zone <zone> to-zone <zone> policy <name>` to see if the policy permits traffic with destination-port any or a wide range
    Affected if The ftps-extensions policy permits traffic from any source to any destination port (permissive data channel)

Device is affected if running an affected Junos version AND has ftps-extensions enabled in a server-facing security policy that permits broad TCP access, allowing clients to reach all ports on the protected FTPS server.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Disable the ftps-extensions option on SRX devices that secure FTPS servers, as this feature is only intended for FTPS client deployments. Review all SRX policies to identify and remediate any instances where ftps-extensions is enabled on server-facing security zones.

Fix this in Junos Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,060
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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-2015-5361 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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