CERT Advisory 072

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CERT Advisory

 · 4 years ago

  

 
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CA-93:19                         CERT Advisory 
                               December 16, 1993 
                      Solaris System Startup Vulnerability 
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The CERT Coordination Center has received information concerning a  
vulnerability in the system startup scripts on Solaris 2.x and Solaris x86 
systems.  The changes described below will be integrated into the upcoming 
Solaris release. 

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I.   Description 

     If fsck(8) fails during system boot, a privileged shell is run 
     on the system console. This behavior can represent a security 
     vulnerability if users, who would normally not have root access, 
     have physical access to the console at boot time.  An attacker 
     can force the failure to occur. 

II.  Impact 

     This vulnerability allows anyone with physical access to the 
     system console to gain root access. 

III. Solution 

     A simple change to each of two system scripts can be used to 
     close this potential security hole. The new behavior will cause the 
     system to run the privileged shell only if the user at the console 
     enters the correct root password. 

     If you wish to make the change on your own systems, edit both 
     /sbin/rcS and /sbin/mountall, changing every occurrence of: 

                /sbin/sh < /dev/console 
     to: 
                /sbin/sulogin < /dev/console 

     As distributed by Sun, /sbin/rcS contains one occurrence of this 
     string, at line 152; and /sbin/mountall contains two, one at line 
     66 and one at line 250. 

     Once these changes are made, sulogin will request the root 
     password in the event fsck(8) fails, before starting a privileged shell. 
     The success or failure of sulogin will be logged in /var/adm/sulog. 

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The CERT Coordination Center wishes to thank Sun Microsystems, Inc. 
for their support in responding to this problem. 
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If you believe that your system has been compromised, contact the CERT 
Coordination Center or your representative in Forum of Incident 
Response and Security Teams (FIRST). 

Internet E-mail: cert@cert.org 
Telephone: 412-268-7090 (24-hour hotline) 
           CERT personnel answer 8:30 a.m.-5:00 p.m. EST(GMT-5)/EDT(GMT-4), 
           and are on call for emergencies during other hours. 

CERT Coordination Center 
Software Engineering Institute 
Carnegie Mellon University 
Pittsburgh, PA 15213-3890 

Past advisories, information about FIRST representatives, and other 
information related to computer security are available for anonymous  
FTP from info.cert.org. 

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