Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)

ExtremeXOS (EXOS) uses a challenge-response mechanism to authorize access to the privileged debug-mode function. The challenge value is generated using an insufficiently random source, which under certain conditions may allow an attacker to predict the expected response and activate debug-mode without authorization. Depending on device configuration and version, this may enable escalation to root-level access and persistent modification of the device software stack. Exploitation requires either a valid low-privilege account on the device (remote scenario) or physical serial console access (local scenario). This vulnerability is distinct from CVE-2017-14329, which addressed a different issue involving Python script privileges. Extreme would like to thank Hadrien Barral (Université Gustave Eiffel) and Georges-Axel Jaloyan (French Ministry of the Interior) for responsible disclosure of their findings.Show less

Dancer2 versions through 2.1.0 for Perl generate insecure session ids when required CSPRNG modules are unavailable. Dancer2::Core::Role::SessionFactory::generate_id silently falls back to a built-in rand-derived session id unless both Math::Random::ISAAC::XS and Crypt::URandom are available. The fallback session id is generated from a SHA-1 hash of a call to the built-in rand function, the absolute path of the Dancer2::Core::Role::SessionFactory module, an internal counter, the process id, the module instance memory address, and a shuffled string of characters (using the List::Util::shuffle function, which also uses the built-in rand function). These are all low-entropy and easily guessed sources. The built-in rand() function is seeded with 32-bits and considered unsuitable for security applications. Predictable session ids could allow an attacker to gain access to systems.Show less

The urwid web display backend (urwid/display/web.py) generates web session identifiers (urwid_id) in Screen.start() by concatenating two random.randrange(10**9) calls that use Python's Mersenne Twister PRNG, which is not cryptographically secure. Each call consumes approximately 30 bits of PRNG state, and the Mersenne Twister internal state is approximately 19,937 bits, so an attacker who observes approximately 334 session IDs (for example via the X-Urwid-ID HTTP response header) can fully reconstruct the internal state and predict all past and future session IDs (Path B). The same identifier is also used as the filename of a FIFO created in the world-listable /tmp directory (for example /tmp/urwid375487765176907690.in), so any local user on the host can list /tmp to enumerate active session tokens directly (Path A). With a valid session ID, an attacker can read the victim's terminal screen via the polling endpoint, inject keystrokes into the victim's session (yielding OS-level code execution with the session owner's privileges if the session runs a shell), and inject exit sequences or flood the FIFO to terminate or crash the session. A prior Bandit S311 warning on this usage was suppressed with # noqa: S311 rather than fixedShow less

GD::SecurityImage versions through 1.75 for Perl use rand to generate secrets. The random method creates the challenge text used for the CAPTCHA by sampling characters from an array using Perl's built-in rand function, and generates a (by default) six-character string. The built-in rand function is unsuitable for security applications because it is predictable and reversible.Show less

WireGuard Easy through 15.3.0, fixed in commit 66b292b, contains a cryptographically weak one-time link token generation vulnerability that allows unauthenticated network attackers to recover WireGuard peer credentials by brute-forcing a keyspace of at most 1000 candidate tokens per client ID, as the token is computed using CRC32 over a random value constrained to 0-999. Attackers can enumerate candidate tokens against the unauthenticated /cnf/:oneTimeLink route, which lacks rate limiting and does not validate token expiration, to obtain a peer's PrivateKey and PresharedKey and impersonate that peer on the VPN network.Show less

Rejetto HFS 3.0.0 through 3.2.0 derives its session-cookie signing key from the non-cryptographic Math.random() generator and discloses outputs of the same generator to unauthenticated clients during login. A remote attacker can collect a small number of login responses, reconstruct the generator's state, recover the signing key, and forge a valid administrator session cookie, leading to full administrative access and remote code execution via the server_code configuration feature.Show less

The DoLogin Security plugin for WordPress is vulnerable to Authentication Bypass via Insufficient Randomness in all versions up to, and including, 4.3. The vulnerability exists because `dologin\s::rrand()` seeds the Mersenne Twister with `mt_srand((double) microtime() * 1000000)` — discarding the integer-seconds component of `microtime()` and constraining the seed to a range of approximately 10^6 values (~20 bits of entropy) — after which every character of the 32-character magic-link token is drawn sequentially with `mt_rand()`, making the entire token a deterministic function of that seed. Because `Pswdless::try_login()` is registered on the unauthenticated `init` hook, resolves the target account by the auto-increment numeric ID embedded in the `?dologin=<id>.<hash>` parameter, performs the hash comparison using a non-constant-time `!=` operator, and then calls `wp_set_auth_cookie()` directly — never passing through `wp_authenticate()` and therefore never triggering the plugin's own `Auth::_has_login_err()` lockout — an unauthenticated attacker can brute-force the ~10^6-candidate seed space to reconstruct an active passwordless login token and authenticate as any targeted user, including administrators, without a password. Exploitation requires that a valid, unexpired passwordless login link (active for up to 7 days) exists for the target account at the time of the attack, and that the numeric link ID is known or guessable from the auto-increment primary key.Show less

CGI::Session::ID::md5 versions before 4.49 for Perl generate predictable session ids from low-entropy sources. The generate_id method builds the session id from a MD5 digest of the process id, the epoch time, and the built-in rand() function. All three are predictable, low-entropy sources: the PID is drawn from a small range, the epoch time can be guessed or read from the HTTP Date header, and Perl's rand() is unsuitable for security purposes because it is predictable and reversible. An attacker who predicts a session id can impersonate the corresponding session and bypass authentication.Show less

UltraVNC through 1.8.2.2 uses inadequate cryptography in the MS-Logon II authentication scheme (rfbUltraVNC_MsLogonIIAuth). In rfb/dh.cpp the Diffie-Hellman key exchange is performed with parameters that fit in an unsigned 64-bit integer (DH_MAX_BITS controls the prime size). A 64-bit DH key can be broken by Pollard's rho algorithm in under one second on current hardware. Additionally, the private exponent is generated by the rng() function, which multiplies three libc rand() values seeded from time(NULL). With approximately 31 bits of internal state and a time-based seed, the private exponent is recoverable in under a minute by a passive observer. A network attacker who can observe the MS-Logon II handshake (via sniffing, recording, or man-in-the-middle) can derive the shared DH key and decrypt the encapsulated username and password, resulting in full credential disclosure. This affects legacy MS-Logon II connections; MS-Logon III (X25519 + AES-256-GCM) is unaffected.Show less

UltraVNC through 1.8.2.2 uses a cryptographically weak pseudo-random number generator to produce VNC authentication challenge bytes. In rfb/vncauth.c:119-129, the vncRandomBytes() function seeds libc rand() with time(0) + getpid() + rand() and generates a 16-byte challenge. The combined seed space is approximately 31 bits (libc rand() internal state) and is entirely determined by publicly-observable values (wall-clock time and process ID). An attacker who can observe the authentication exchange can enumerate the seed space and predict the challenge within seconds, enabling forgery or offline brute-forcing of responses. Note: on Windows, the active code path may use vncEncryptBytes2.cpp which calls CryptGenRandom; reachability on shipped Windows binaries requires compile-graph verification and is under investigation.Show less

Net::BitTorrent versions before 2.1.0 for Perl generate the MSE Diffie-Hellman private key with a non-cryptographic PRNG. The MSE (Message Stream Encryption) handshake derives its 160-bit Diffie-Hellman private key from Perl's rand(), a non-cryptographic drand48-class generator seeded once per process, in KeyExchange.pm. The shared secret and the RC4 keys derived from it (the SHA-1 of "keyA" or "keyB", the shared secret, and the infohash) therefore depend entirely on a predictable PRNG. The same handshake sends, in cleartext, random padding drawn from the same rand() sequence in _random_pad, immediately after the public key and the private-key draw. A passive observer of the handshake recovers the PRNG state from the cleartext padding, reconstructs the private key, computes the shared secret from the peer's public key on the wire, derives the RC4 keys, and decrypts the connection, defeating the passive-observation obfuscation MSE provides.Show less

Mojolicious::Plugin::Web::Auth::OAuth2 versions through 0.17 for Perl have an insecure default state parameter. When no state generator is specified in the constructor, the module defaults to using a SHA-1 hash of predictable and low-entropy sources, including the epoch time (which is leaked via the HTTP Date header) and a call to Perl's built-in rand function. A predictable state allows an attacker to hijack another user's session through cross site request forgery (CSRF).Show less

Mojolicious::Sessions::Storable versions through 0.05 for Perl generate session ids insecurely. The default session id generator returns a SHA-1 hash seeded with the built-in rand function, the epoch time, the heap address of an anonymous hash, and the PID. These are predictable or low-entropy sources that are unsuitable for security purposes.Show less

The linqi application contains hardcoded cryptographic keys. Additionally, the application uses a weak algorithm with a limited ASCII charset to dynamically generate Initialization Vectors (IVs) for AES/CBC encryption, making known-plaintext attacks feasible. An attacker with local access can leverage these vulnerabilities to decrypt sensitive obfuscated strings, including ConnectionString values containing database credentials from appsettings.json.Show less