D-Tale Weak SECRET_KEY Causes Session Forgery and Authentication Bypass

Vulnerability Overview Vulnerability Name: Weak Flask SECRET_KEY Leads to Session Forgery / Authentication Bypass #960 Vulnerability Type: CWE-331: Insufficient Entropy CWE-330: Use of Insufficiently Random Values CWE-338: Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG) Impact: CWE-384 (Session Fixation Forgery) / CWE-287 (Improper Authentication) CVSS 3.1: Base Score: 6.5 (Medium) Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N Justification: - AC:L - The login page and signed session cookies are accessible over the network. - AV:N - Success depends on conditions outside the attacker's control: (1) Authentication must be explicitly enabled ( ), which is not the default D-Tale configuration; (2) The attacker must obtain a target-signed cookie, then brute-force a 2^51.7 key space (crackable within hours on a GPU cluster, not via a single trivial request). - PR:N / UI:N - No credentials or user interaction required: Once authentication is enabled, unauthenticated visitors obtain a signed session cookie with a simple request to the login page. - C:H - A forged grants read-only access to all datasets loaded into the D-Tale process. - I:H - Data tampering endpoints become accessible, but they operate on transient DataFrame views in memory held by the process, not on persistent system data, credentials, or storage records; therefore, the integrity impact is limited rather than systemic. - A:N - No direct availability impact. Vulnerability Description: When authentication is enabled, D-Tale protects its routes via Flask sessions. Upon successful login, the server stores the session . The decorator authorizes subsequent requests solely by reading these two session values. Flask session cookies are client-side and protected by an HMAC signature using the application's . D-Tale generates the at startup by using to select 10 characters from an alphabet of only 36 symbols (A-Z and 0-9). This results in a key space of 2^51.7, presenting two combinatorial weaknesses compared to Flask's recommendation of (2^192): 1. Low Entropy - 2^51.7 is vulnerable to offline brute-force attacks. At ~10^10 HMAC verifications/second (on commodity GPU clusters), the average time to crack is 2.1 days, requiring no interaction with the server. 2. Weak PRNG - (Mersenne Twister) is not a cryptographically secure RNG. Its internal state can be recovered from its output, and it is not intended for secret generation, further weakening practical security. Any unauthenticated client can obtain a signed (unauthenticated) session cookie simply by accessing . An attacker uses this cookie as an online oracle to recover the , then generates a signed cookie carrying , bypassing authentication regardless of password strength or rate limits. Scope of Impact Components: ( ), session authentication in . Prerequisites: Authentication must be enabled ( ). Default D-Tale deployments run without authentication and are not within the specific bypass scope. Remediation Generate keys using a CSPRNG with sufficient length, such as or (≥2^256). Stop using for secret generation. Persist the key in a configuration file (via the environment variable) to ensure a strong value is generated once and can be audited. Optionally set , , and to reduce the surface area for cookie capture. POC Code

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D-Tale Weak SECRET_KEY Causes Session Forgery and Authentication Bypass

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