| QNAP TS-251+ (TS-251+-2G)
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Security Grade
Calculator v
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QNAP TS-251+ 2-bay NAS (TS-251+-2G)
Release Date: 2015-11-10 • Status:
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Security Evaluation
1. Device Security
| Criterion
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Value
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Proof
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Comment
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| Known hardware tampering
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Rare
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🔗 Proof
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A model-specific hands-on report (August 2025) demonstrates changing the BIOS boot order and starting Debian from an external USB port on a TS-251+. This fits the methodology's physical-access/port-modification scope. Rare is a qualitative rating for a documented example, not a measured incident rate. This is an owner modification, not evidence of a malicious hardware attack.
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| Known vulnerabilities
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Very common
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🔗 Proof
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QSA-25-51 documents five CVEs affecting QTS 5.2.x, with fixes in QTS 5.2.8.3332 build 20251128 and later. QNAP also documents earlier QTS security incidents. Very common is a qualitative assessment of recurring platform vulnerabilities, not a measured frequency. Applicability depends on installed firmware and apps; this does not show that a fully patched TS-251+ remains vulnerable.
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| Prior attacks
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Rare
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🔗 Proof
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Anomali's July 2019 eCh0raix analysis lists a TS-251+ running reported firmware 4.3.1.0695 Build 20180830 among affected devices. Anomali analyzed the malware; the exact model/firmware entry is attributed to victim forum reports, not an independently verified device test. Rare denotes a documented historical model-specific report. Population frequency is unknown, and no current compromise is asserted.
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| Updatability
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Very common
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🔗 Proof
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Official release notes list TS-251+ for QTS 5.2.9.3492 (May 2026) and QTS 5.2.11.3652 (October 2026); the model catalog lists QTS 5.2.11. Very common reflects continuing, repeated firmware releases, not a fixed update schedule. The exact model-specific security-support end date has not been verified. Legacy hardware status does not mean updates are unavailable.
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| Category Score
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Score: 2 / 3
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2. System Security
| Criterion
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Value
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Proof
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Comment
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| Authentication with other systems
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Partial
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🔗 Proof
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QTS supports one-way and mutual CHAP for iSCSI. The documented default CHAP setting is one-way, while mutual CHAP is optional and No CHAP is also selectable. Partial therefore reflects authentication that is configurable and not universally mutual. It does not claim that every service lacks authentication.
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| Communications
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No encryption
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🔗 Proof
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QTS documents HTTP administration on port 8080 and optional HTTPS with TLS and an HTTPS-only setting. The score concerns the documented plaintext HTTP path when HTTPS-only is not enforced. HTTPS/TLS is supported. It would be incorrect to describe all communications as unencrypted or all deployments as using this configuration.
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| Storage
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No encryption
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🔗 Proof
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QNAP documents direct access to the flash configuration partition on HAL-based Intel NAS. A TS-251+ owner on QTS 4.5.1.1495 (December 2020) reports reading filesystem entries directly from /dev/sdc6 and shows ext2 DOM partitions. Together these support No encryption for that documented flash filesystem, an assessment inference from positive evidence. They do not establish every flash area's protection or verify QTS 5.2.11. Optional AES-256 disk-volume/folder encryption is a separate capability.
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| Category Score
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Score: 3 / 3
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3. User Authentication
| Criterion
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Value
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Proof
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Comment
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| Account management
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Full
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🔗 Proof
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QTS provides local users and groups, user deletion and password changes, with shared-folder and application privileges. This supports Full account-management capability, including users with fewer privileges. It does not assert that a particular installation follows least privilege.
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| Authentication
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Basic
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🔗 Proof
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QTS supports account passwords and optional two-step verification. QNAP documents a physical reset procedure that restores administrator and security settings. Basic reflects the recovery path when hardware reset is enabled, alongside the available password-only mode. It does not mean two-step verification is absent, or establish a current hard-coded remote backdoor.
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| Brute-force protection
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Exist
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🔗 Proof
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QTS can block a client IP after a configurable number of failed logins in a time interval and set the blocking duration. Exist reflects this documented protection. Coverage depends on selected protocols and configuration; it is not a guarantee against every distributed attack.
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| Event logging
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Access event logged
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🔗 Proof
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QuLog Center provides access logs searchable by user and source IP. A log destination must be configured to enable access logging. Access event logged therefore represents the documented capability once configured, not an assertion that logging is enabled on every installation.
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| Passwords
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Require change after setup
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🔗 Proof
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QTS 5.2.x initialization requires choosing a new administrator password. This is mapped to the intermediate change-at-setup rating, not a claim of mandatory periodic changes. The password-policy page specifies a default minimum of eight characters and a digit, while the HDMI initializer documents a 1-64-character range. Universal complexity enforcement across setup paths remains unverified; complexity controls do exist.
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| Category Score
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Score: 2 / 3
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Technical Specifications
| Property
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Details
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| Operating System & App
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QTS; current model catalog lists QTS 5.2.11. QTS 5.2.x controls assessed; historical flash findings are dated separately. (Companion App: Qmanager)
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| Hardware (CPU / GPU)
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CPU: Intel Celeron J1900, 4 cores, 2.0 GHz base, up to 2.42 GHz burst • GPU: Intel HD Graphics
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| Memory & Storage
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Memory: 2 GB DDR3L SODIMM; official maximum 8 GB (2 x 4 GB) • Storage: 512 MB boot flash; 2 SATA bays for HDD/SSD; sold diskless
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| Power, Battery & Charging
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Battery: • Power: 60 W / 65 W external adapter, 12 VDC output, 100-240 VAC input • Charging:
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| Display & Camera
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Display: Power/status, LAN, USB and HDD LEDs; HDMI output up to 1080p • Camera:
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| Sound & Connectivity
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Sound: System-warning buzzer; HDMI audio output • Connectivity: 2 x Gigabit Ethernet RJ45; 2 x USB 2.0; 2 x USB 3.2 Gen 1; HDMI; IR receiver
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| Physical (Dimensions & Mass)
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Dimensions: 168.5 x 102 x 225 mm (H x W x D) • Mass: 1.28 kg (net)
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Assessment scope and evidence limitations
Reviewed on 23 October 2026. Exact model: TS-251+; the general specifications refer to the TS-251+-2G SKU. This is distinct from the original TS-251 already listed in Wiki-IoT. Station search and the existing TS-251 form were checked before drafting.
This is a documentary assessment of capabilities and exposure paths, not a hands-on test or a claim about one uniform default configuration. Software controls use QTS 5.2.x documentation, supported by current model-specific release notes. Hardware modification evidence is dated August 2025, ransomware evidence July 2019, and direct flash-filesystem evidence December 2020 (QTS 4.5.1.1495). The historical flash finding is not a fresh test of QTS 5.2.11. HTTP scoring concerns the available plaintext administration path when HTTPS-only is not enforced. Logging and IP-blocking scores describe documented configurable capabilities.
Unknowns: population rates of tampering and attacks; exact security-support end date; encryption coverage of every flash area on current firmware; universal password-complexity enforcement across initialization paths. The site has no Unknown option or numerical frequency thresholds. Rare/Very common are qualitative judgments; missing evidence has not been scored as None or Absent. The model-specific attack entry cited by Anomali ultimately comes from victim reports. The flash inference combines vendor documentation with a historical first-person technical report; it is not vendor certification.
The catalog labels the model Legacy. Because an exact mapping to the form's In sale / End of sale / End of life states was not verified, Status is left blank. Release date is the manufacturer's public announcement, not independently verified first shipment. Parent company, generation, battery, charging and camera fields are left blank rather than filled with unsupported claims.
General-information sources
Official specifications: https://www.qnap.com/en-me/product/ts-251%2B/specs/hardware
Official release announcement (10 November 2015): https://www.qnap.com/en/news/2015/qnap-releases-high-value-quad-core-nas-ts-251-and-ts-451-supporting-virtualization-encryption-transcoding-and-hdmi-output
QTS 5.2.x guide: https://docs.qnap.com/operating-system/qts/5.2.x/qts5.2.x-ug-en-us.pdf
Additional evidence URLs
