CVE-2023-41927

Executive Summary

CVE-2023-41927 is a cryptographic configuration weakness in Kiloview P1/P2 network video encoder/decoder devices. The embedded TLS server of these appliances accepts at least one cipher suite on the Dutch NCSC-NL "to be phased out" list, meaning the device may negotiate deprecated, cryptographically weak protection for management and possibly streaming sessions. Successful exploitation, carried out by an on-path or passive network adversary, risks exposure of administrative credentials and sensitive video control traffic, although the CVSS base score of 5.3 (Medium) and the very low EPSS score indicate limited real-world exploitation urgency. No public exploit code, no Nuclei template, and no CISA KEV listing are currently associated with this CVE.

Technical Analysis

The vulnerability is not a memory-corruption or logic flaw in application code; it is a weak-cipher configuration issue in the TLS stack of Kiloview P1/P2 devices. According to the NVD description, "The server supports at least one cipher suite which is on the NCSC-NL list of cipher suites to be phased out." The NCSC-NL (Dutch National Cyber Security Centre) maintains an advisory list of cryptographic algorithms and cipher suites that are considered cryptographically weak or obsolete and should be disabled — examples include RC4, 3DES/EDE-CBC, and AES-CBC suites without forward secrecy, among others.

From a protocol standpoint, the flaw manifests in the TLS handshake. When a client connects to any TLS-protected listener on the device (plausibly the embedded web management interface used to configure the P1/P2 encoders/decoders), the server advertises its accepted cipher suites in the ServerHello or accepts a ClientHello proposal of a weak suite. If the server's default priority list includes a suite flagged by NCSC-NL, one of two outcomes occurs:

1. Client-initiated negotiation — an attacking client simply requests the weak suite and the server accepts it without policy enforcement.
2. Passive/malicious downgrade — an active man-in-the-middle (MITM) attacker alters the offered cipher list during handshake to force the weakest common suite.

The cryptographic weaknesses of the affected suites are well documented at the algorithm class level. RC4 suffers from statistical bias in key-stream bytes, allowing plaintext recovery after capturing a sufficiently large volume of ciphertext. 3DES has a 64-bit block size, enabling birthday-bound collision attacks (the SWEET32 class) when tens of gigabytes of traffic are encrypted under the same key. CBC-mode cipher suites may be subject to padding-oracle style attacks when combined with MAC-then-Encrypt construction (POODLE-class behavior). All of these weaken the confidentiality guarantees of sessions used to administer the device.

The attack surface is any network path that terminates TLS on the Kiloview P1/P2 device. These are hardware appliances for professional video-over-IP workflows (encoding/decoding HDMI/SDI signals for live production, broadcast, and IP distribution). As embedded appliances, they are frequently deployed at the network edge — in broadcast trucks, production studios, campus distribution points — and may expose management TLS ports to local networks, or, in misconfigured deployments, to the internet. The NVD description does not identify the exact listener or service that presents the weak cipher suite, and no code-level detail (function names, file paths, or API endpoints) is disclosed in the CVE data. Per the supplied CVE data, no CWE has been formally assigned by NVD; the weakness maps most directly to CWE-327.

Notably, the affected version list is empty and no concrete patch data is available. The patch confidence rating is 2/4 ("CLAIMED"): a single source — the CNA (assumed to be Kiloview or an affiliate) — states that a fix exists, but no independent verification, advisory URL, firmware version, or release timeline has been published.

Exploitation Scenarios

No public PoC exists, no exploit code is available, and no Nuclei template covers this CVE. The attack chain below is therefore inferred from the vulnerability class (weak cipher suite support) in accordance with the NVD description.

Step 1 — Reconnaissance / target identification. An attacker identifies internet- or network-facing Kiloview P1/P2 devices. This is accomplished via passive search-engine gathering (Shodan/Censys/fofa using banners such as "Kiloview") or active network scanning of the management subnet. TLS enumeration with tools such as nmap (script ssl-enum-ciphers) or sslscan confirms the device's cipher-suite support and reveals that a weak suite is enabled. No endpoint names or paths are required; the vulnerability is exposed at the TLS protocol layer.

Step 2 — Flaw trigger / session negotiation. The attacker establishes a TLS session with the affected listener (for example, the HTTPS management interface). Either the device's own preference order selects a weak suite, or the attacker, acting as an adversary-in-the-middle between the legitimate administrator and the device, strips strong suites from the ClientHello/ServerHello exchange (a classic protocol-downgrade technique) so that the negotiated session lands on a suite flagged by NCSC-NL — e.g., an RC4 or 3DES-CBC suite.

Step 3 — Payload / execution method. There is no injected payload in the traditional sense; the "execution" is traffic capture and cryptanalysis. The attacker records the TLS ciphertext of the administrator's session. Depending on the negotiated suite, the attacker performs: (a) RC4 bias analysis requiring roughly hundreds of megabytes of captured traffic, (b) SWEET32-style birthday attacks on a 64-bit block cipher requiring a few tens of gigabytes of captured ciphertext to recover secrets such as HTTP session cookies or credentials, or (c) a downgrade-then-CBC attack if the suite is vulnerable to padding-oracle behavior. The result is recovery of plaintext application data — most importantly the administrator's session cookie or submitted credentials.

Step 4 — Post-exploitation impact. With recovered administrative credentials or a valid session token, the attacker logs into the Kiloview device management interface. Depending on the device's feature set, this can allow reconfiguration of the encoder/decoder (stream destinations, RTMP/RTSP/SRT outputs), exfiltration of the live video stream, injection of malicious stream conFiguration, or lateral movement into the broadcast/video network segment. Even without credential recovery, a passive attacker can decrypt captured video-control metadata and compromise the confidentiality of production content. In real-world CCTV/live-production environments, this may equate to exposure of unreleased media or surveillance footage, with regulatory and reputational consequences.

Impact Assessment

The CVSS base score of 5.3 classifies CVE-2023-41927 as Medium severity. Although the published vector is not available, the vulnerability class and protocol-layer nature imply a primarily Confidentiality impact (plaintext disclosure) with a secondary Integrity concern if session manipulation — for example, ciphertext reordering or stream injection — is achievable. The attack typically requires an active on-path position (MITM) to force a downgrade, which raises the attack complexity; this is consistent with the moderate score.

Affected systems: Kiloview P1 and P2 encoder/decoder hardware running firmware versions that include the vulnerable TLS configuration. Because the affected version range is undisclosed, operators must assume all firmware releases up to the CNA-claimed fix are potentially vulnerable.

Blast radius: The immediate blast radius is the device itself — compromise of its TLS sessions exposes the management plane. The broader blast radius extends to the production video pipeline the device serves: any captured video, encoder settings, or stream-destination credentials (e.g., server passwords for RTMP/SRT publishing) become readable by the attacker. In multi-tenant facilities (rental broadcast infrastructure, OB trucks, video-over-IP campus networks), one vulnerable encoder can become a foothold for lateral movement into adjacent production systems.

Exploitation likelihood: EPSS is 0.00133 (3.3rd percentile), indicating a very low probability of exploitation in the near term. The CVE is not listed in CISA's Known Exploited Vulnerabilities catalog, there is no known exploit code, and no threat-actor campaigns referencing this CVE have been observed as of the data date. The absence of a confirmed patch (confidence 2/4) is nonetheless concerning for asset owners, as the vulnerability will persist in deployed firmware until Kiloview publishes and operators apply the fix.

Detection Guidance

Detection of this weakness focuses on two classes of indicators: (1) TLS fingerprinting of the device negotiating a weak cipher suite, and (2) network telemetry of cipher suites seen in server hello messages. The rules below operate at the protocol/flow level and are intentionally generic enough to be adapted to different log sources.

Sigma Rule

title: Weak TLS Cipher Suite Negotiated with Kiloview P1/P2 Device
id: c7f4e94f-3c2b-4a0e-9d46-8f1a6b3c2d10
status: experimental
description: >
  Detects TLS sessions where a server negotiates a cipher suite flagged by
  NCSC-NL for phase-out (RC4, 3DES, DES, NULL, EXPORT). Designed for
  environments where Kiloview P1/P2 devices are present.
date: 2024/06/01
author: Valters IT Threat Intelligence
logsource:
  category: network_connection
  product: zeek
detection:
  selection_weak_ciphers:
    ssl.cipher|contains:
      - '3DES'
      - 'RC4'
      - 'DES-CBC'
      - 'NULL'
      - 'EXPORT'
    ssl.server_name|endswith:
      - '.local'      # common mDNS/LAN naming, adjust per environment
  condition: selection_weak_ciphers
falsepositives:
  - Legacy monitoring tools that intentionally use weak ciphers
  - Non-Kiloview network equipment with the same TLS misconfiguration
level: medium

YARA Rule

This rule scans packet captures (PCAP files) or firmware/config artifacts for TLS ServerHello records carrying a weak cipher suite, or for embedded strings referencing deprecated OpenSSL cipher names.

rule Weak_TLS_Cipher_Kiloview_P1P2
{
    meta:
        author = "Valters IT Threat Intelligence"
        description = "Detect TLS ServerHello or binary strings indicating RC4/3DES/DES weak cipher support (CVE-2023-41927, Kiloview P1/P2)"
        reference = "CVE-2023-41927"
        date = "2024-06-01"
    strings:
        $s_3des = "TLS_RSA_WITH_3DES_EDE_CBC_SHA" ascii wide
        $s_rc4_1 = "TLS_RSA_WITH_RC4_128_SHA" ascii wide
        $s_rc4_2 = "TLS_RSA_WITH_RC4_128_MD5" ascii wide
        $s_des  = "TLS_RSA_WITH_DES_CBC_SHA" ascii wide
        $tls_hdr = { 16 03 03 }                         // TLS 1.2 handshake record header
        $cs_3des = { 00 0A }                            // cipher_suite 0x000A TLS_RSA_WITH_3DES_EDE_CBC_SHA
        $cs_rc4  = { 00 05 }                            // cipher_suite 0x0005 TLS_RSA_WITH_RC4_128_SHA
    condition:
        uint16(0) == 0xA1B2 or uint32(0) == 0x0A0D0D0A // PCAP or pcapng magic
        and ( any of ($s_*) or ( $tls_hdr at 0 and ( $cs_3des in (0..512) or $cs_rc4 in (0..512) ) ) )
        or any of ($s_*)
}

Suricata IDS Rule

alert tls any any -> any any ( \
    msg:"CVE-2023-41927 - Weak TLS cipher suite negotiated with Kiloview P1/P2 device"; \
    tls.ciphers:"3DES|RC4|DES-CBC|NULL|EXPORT"; \
    tls.server_hello; \
    flow:established,to_server; \
    threshold: type both, track by_src, count 3, seconds 60; \
    reference:cve,2023-41927; \
    classtype:policy-violation; \
    sid:20234192; rev:1;)

Elastic Detection

EQL correlation over network events where a TLS server hello advertises a weak cipher suite:

sequence by host.ip, destination.ip, destination.port
  [ network where network.protocol == "tls" and tls.server_hello == true
      and (tls.cipher : "*3DES*" or tls.cipher : "*RC4*" or tls.cipher : "*DES-CBC*"
           or tls.cipher : "*NULL*" or tls.cipher : "*EXPORT*") ]
  [ authentication where event.action in ("login", "authentication_success")
      and process.name : "*" ] /* optional: correlate with subsequent auth events */

Splunk SPL Query

index=network sourcetype="bro:ssl:json" OR sourcetype="zeek:ssl"
| where match(cipher, "(?i)(3des|rc4|des-cbc|null|export)")
| stats count earliest(_time) latest(_time) by src_ip, dest_ip, dest_port, cipher, server_name, ja3s
| where count > 3
| eval alert="Potential CVE-2023-41927 Weak TLS Cipher Activity"
| table _time, alert, src_ip, dest_ip, dest_port, cipher, server_name, count

Wazuh OSSEC Rule

<group name="tls,network,">
  <rule id="100345" level="6">
    <decoded_as>json</decoded_as>
    <field name="cipher">\.?(?i)(3DES|RC4|DES-CBC|NULL|EXPORT)</field>
    <description>CVE-2023-41927: Weak TLS cipher suite observed in network traffic (possible Kiloview P1/P2).</description>
    <options>no_full_log</options>
    <group>tls_weak_cipher,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence is 2/4 (CLAIMED): the CNA asserts that a fix exists, but this has not been independently confirmed, no advisory has been published, and no patched firmware version has been identified. Until Kiloview publicly releases and validates a fix, treat all P1/P2 devices as vulnerable.

1) Immediate mitigations (no vendor patch required):

• Restrict management interfaces (HTTPS web UI, CLI) to trusted administrative networks/IP allowlists; do not expose them directly to the internet. If remote management is required, place the device behind a VPN or jump host.
• Terminate TLS at a reverse proxy / load balancer with a current, hard-coded cipher policy (e.g., TLS 1.2+ with ECDHE+AESGCM). This removes the device's weak TLS from the network path for external clients.
• Use network-layer segmentation (VLANs, firewall rules) to isolate Kiloview devices from general user traffic, reducing MITM and passive-capture exposure.
• If the device firmware allows TLS settings to be configured, disable all TLS versions below 1.2 and remove RC4/3DES/DES/NULL/EXPORT suites.

2) Patch / upgrade steps:

• Contact Kiloview support or the CNA directly to obtain the referenced fix; confirm the affected-version range and patched firmware version before deployment.
• Upon release of a patched build, apply it to every P1/P2 unit in the fleet during a maintenance window; verify firmware integrity against the vendor's published checksums.
• After upgrading, re-run a cipher-suite audit (nmap --script ssl-enum-ciphers / sslscan) on each device to confirm that no NCSC-NL phase-out suites remain enabled.

3) Long-term hardening:

• Adopt the NCSC-NL cipher-suite recommendations (or industry equivalent such as NIST SP 800-52r2) as the baseline for all TLS-enabled network appliances in the environment.
• Monitor CVE-2023-41927 and vendor advisories for updated patch information; reassess exposure when the patch confidence improves or version information is disclosed.
• Implement centralized TLS/network logging (Zeek/Suricata/Elastic) so that newly discovered weak-cipher devices can be detected organization-wide.
• Rotate any credentials that may have traversed vulnerable Kiloview sessions, especially production stream-publishing credentials (RTMP/SRT server keys and passwords).

References

• NVD Entry — CVE-2023-41927: https://nvd.nist.gov/vuln/detail/CVE-2023-41927
• NCSC-NL — "Weak cryptographic algorithms" (list of cipher suites to be phased out): https://english.ncsc.nl/publications/publications/2020/january/16/weak-cryptographic-algorithms
• Kiloview official product site (P1/P2 encoder series): https://www.kiloview.com
• CISA Known Exploited Vulnerabilities Catalog (no entry for CVE-2023-41927 as of data date): https://www.cisa.gov/known-exploited-vulnerabilities-catalog

No threat-actor campaigns, in-the-wild exploitation evidence, or public exploit code for CVE-2023-41927 have been observed as of the intelligence date. The exploitation likelihood (EPSS 0.00133) is low, but the unresolved patch status warrants continued monitoring.