Re: SSH 1.x and 2.x Daemon

From: Yutaka OIWA (yutakaat_private)
Date: Mon Jan 25 1999 - 08:16:55 PST

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    >> On Sat, 23 Jan 1999 17:06:44 -0500, KuRuPTioN <kuruptionat_private> said:
    
    KuRuPTioN> There seems to be incomplete code in the SSH daemon in both versions 1.2.27
    KuRuPTioN> and 2.0.11 (only tested).  The bug simply allows users who with expired
    KuRuPTioN> accounts (in /etc/shadow) to continue to login even though other such
    KuRuPTioN> services such as ftp and telnet deny access.  Here is the log using 1.2.27
    KuRuPTioN> (but the same happens with 2.0.11).
    
    It seems to be a bug of configure script.  As my quick observation
    for source code, possibly-vulnerable environment is
    
      - sshd 1.2.26 on
          * Linux, Irix5, Irix6, Ultrix, Convex
      - sshd 2.0.11 on
          * Almost all platform with account expiration and without
            usersec.h(?)
    
    To check whether the sshd is vulnerable, execute the command
    
      strings sshd | grep expire
    
    and see whether the message for ACCOUNT expiration is exist.
    (There may be a message for password expiration)
    
    Adding
      #define HAVE_STRUCT_SPWD_EXPIRE 1
    to appropriate header file (do after ./configure) may solve the
    problem (sorry, not tested).
    
    Detail:
      In ssh 1.2.26, checking shadow passwd existence is bypassed on
      some platforms. However, checking sp_expire existence is done
      in the bypassed section of configure script.
      In ssh 2.0.11, no checking seems to be done for sp_expire. (true?)
    
    --
    Yutaka Oiwa      Yonezawa Lab., Department of Information Science,
                              Faculty of Science, University of Tokyo.
      Email: <oiwaat_private-tokyo.ac.jp>, <yutakaat_private>
    PGP fingerprint = C9 8D 5C B8 86 ED D8 07  EA 59 34 D8 F4 65 53 61
    



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