Amon2 versions before 6.17 for Perl use an insecure random_string implementation for security functions. In versions 6.06 through 6.16, the random_string function will attempt to read bytes from the /dev/urandom device, but if that is unavailable then it generates bytes by concatenating a SHA-1 hash seeded with the built-in rand() function, the PID, and the high resolution epoch time. The PID will come from a small set of numbers, and the epoch time may be guessed, if it is not leaked from the HTTP Date header. The built-in rand function is unsuitable for cryptographic usage. Before version 6.06, there was no fallback when /dev/urandom was not available. Before version 6.04, the random_string function used the built-in rand() function to generate a mixed-case alphanumeric string. This function may be used for generating session ids, generating secrets for signing or encrypting cookie session data and generating tokens used for Cross Site Request Forgery (CSRF) protection.
In versions 6.06–6.16, the random_string function attempts to read bytes from /dev/urandom, but when this device is unavailable, it generates bytes as a concatenation of an SHA-1 hash initialized with the built-in rand() function, the process PID, and high-resolution epoch time. The PID comes from a limited range of values, and the epoch time can be guessed or leaked via the HTTP Date header. In versions before 6.06, there was no fallback mechanism when /dev/urandom was unavailable, whereas before version 6.04, the function used only rand() to generate alphanumeric strings. Perl's built-in rand() function is not suitable for cryptographic applications.
An attacker can predict or reproduce values generated by random_string, enabling user session hijacking, forgery of signed or encrypted cookies, and bypassing Cross Site Request Forgery (CSRF) protection.
Amon2 should be updated to version 6.17 or newer, which contains a fixed implementation of random_string. The update is available in the CPAN repository at metacpan.org/release/TOKUHIROM/Amon2-6.17.
Tokuhirom Amon2 for Perl — all versions before 6.17 (particularly versions before 6.04, 6.04–6.05, and 6.06–6.16)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HTokuhirom Amon2
APPTokuhirom< 6.17
Related vulnerabilities
UnQLite dla Perl — osadzona nieaktualna biblioteka z potencjalnym heap overflow
Amon2::Plugin::Web::CSRFDefender versions from 7.00 through 7.03 for Perl generate an insecure session id. Th...
HTTP::Session2 versions through 1.09 for Perl does not validate the format of user provided session ids, enabl...
HTTP::Session2 versions before 1.12 for Perl for Perl may generate weak session ids using the rand() function....