The original advisory [RSI.0010.10-21-98.IRIX.AUTOFSD] was sent to Silicon 
Graphics Inc. on Fri, 2 Oct 1998 17:48:43, and detailed a local vulnerability
against the 'autofsd' daemon. 

Further testing has revealed that this issue extends to remote attackers
on the Irix platform as well as the AIX platform. 

SGI was contacted again on Wed, 11 Nov 1998 18:57:07 and made aware of the
remote vulnerability. Mention of the remote vulnerability has been made in
SGI's security adivsory [19981005-01-PX] as well as IBM's advisory 
[ERS-SVA-E01-1998:004.1].

RSI is releasing the following update to disclose further details on the
attack.


RSI.0010a.11-29-98.IRIX.AUTOFSD



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                   Repent Security Incorporated, RSI
                       [ http://www.repsec.com ]


           *** RSI ALERT ADVISORY ***
 

--- [CREDIT] --------------------------------------------------------------

Mark Zielinski : Discovered the vulnerability, author of the advisory


--- [SUMMARY] -------------------------------------------------------------

Announced:     October 2, 1998
Report code:   RSI.0010a.11-29-98.IRIX.AUTOFSD
Report title:  IRIX autofsd

Vulnerability: Please see the details section 
Vendor status: SGI contacted on October 2, 1998
Patch status:  Information on patches is available

Platforms:     AIX 4.3, IRIX 6.2, 6.3, 6.4, 6.5, 6.5.1

Update:        Previous advisory listed this as a local issue. Further
               testing indicates this is remotely vulnerable.

Reference:     http://www.repsec.com/advisories.html
Impact:        If exploited, an attacker could potentially compromise
               root access both locally and remotely on your server

NOTE:          IRIX versions 5.3, 6.0, and 6.1 were NOT tested by RSI, 
               however they could be subject to the same vulnerability.

               AIX 4.1.x and 4.2.x are NOT vulnerable.


--- [DETAILS] -------------------------------------------------------------

Description:   Autofsd is an RPC server which answers file system mount
               and umount requests from the autofs file system.  It uses  
               local files or name service maps to locate file systems to
               be mounted.

Problem:       Remote users can send requests to the autofsd daemon
               and execute arbitrary commands as the superuser.

               Since the autofsd daemon runs as root on a fixed UDP port,
               it becomes very dangerous.  This will allow any hacker
               to remotely connect straight to the port without having
               to ask the portmapper.

               It is a common mistake for system administrators to 
               disable portmapper but forget about the rpc services 
               running in the background.

Details:       Upon receiving a map argument from a client,
               the server will attempt to verify if it is executable 
               or not.  If autofsd determines the map has an executable
               flag, the server will append the client's key and attempt
               to execute it.

               By sending a map name that is executable on the server,
               and a key beginning with a semicolon or a newline followed
               by a command, unprivileged users can execute arbitrary
               commands as the superuser.

               The problem occurs when the server appends the key
               to the map and attempts to execute it by calling
               popen.

               Since popen executes the map and key you specify by
               invoking a shell, it is possible to force it into executing
               commands that were not meant to be executed.


--- [THANKS] --------------------------------------------------------------

RSI would like to thank APK for his input on the remote aspect of this
vulnerability.


--- [FIX] -----------------------------------------------------------------

Solution:      SGI patch information can be found in their advisory located 
               at: ftp://sgigate.sgi.com/security/19981005-01-A

               IBM is working on the following fixes which will be available soon.

               AIX 4.1.x:  not vulnerable
               AIX 4.2.x:  not vulnerable
               AIX 4.3.x:  IX83752

               AIX patch can be found at: ftp://aix.software.ibm.com/aix/efixes/security/automountd.tar.Z

               Filename          sum             md5
               ==================================================================
               autofs.ext        26103   117     4afedf8fbe411e8be2588fa8843211ae
               automountd        16386    83     eb4c2e1c4cfe609b2ecba0c6a704640c


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Repent Security Incorporated (RSI)
13610 N. Scottsdale Rd.
Suite #10-326
Scottsdale, AZ 85254

E-Mail: advise@repsec.com
FTP: ftp://ftp.repsec.com
WWW: http://www.repsec.com

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