This weakness involves creating non-standard or non-tested algorithms, using weak algorithms or applying cryptographic algorithms incorrectly. Algorithms that were once considered safe are commonly later found to be unsafe, as the algorithms were broken.
The crypt functions use a poor one-way hashing algorithm; since they only accept passwords of 8 characters or fewer and only a two-byte salt, they are excessively vulnerable to dictionary attacks given today's faster computing equipment.
alpine-2.20/imap/src/osdep/unix/ckp_std.c
The highlighted line of code below is the trigger point of this particular Fedora 24 crypto weakness.
*
* Author: Mark Crispin
* Networks and Distributed Computing
* Computing & Communications
* University of Washington
* Administration Building, AG-44
* Seattle, WA 98195
* Internet: MRC@CAC.Washington.EDU
*
* Date: 1 August 1988
* Last Edited: 30 August 2006
*/
/* Check password
* Accepts: login passwd struct
* password string
* argument count
* argument vector
* Returns: passwd struct if password validated, NIL otherwise
*/
struct passwd *checkpw (struct passwd *pw,char *pass,int argc,char *argv[])
{
return (pw->pw_passwd && pw->pw_passwd[0] && pw->pw_passwd[1] &&
!strcmp (pw->pw_passwd,(char *) crypt (pass,pw->pw_passwd))) ?
pw : NIL;
}