=============================================================================
CA-94:09 CERT Advisory
May 23, 1994
/bin/login Vulnerability
-----------------------------------------------------------------------------
The CERT Coordination Center has learned of a vulnerability in
/bin/login. This vulnerability potentially affects all IBM AIX 3
systems and Linux systems. At this time, we believe that only
IBM AIX 3 and Linux systems are at risk.
Included with this advisory is an appendix containing the
CA-94:09.README, which lists the vendors who have responded to our
inquiries, and the status of their investigation into this
vulnerability report. As we receive additional information relating
to this advisory, we will place it, along with any clarifications, in
the README file, available via anonymous FTP from info.cert.org. We
encourage you to check the README files regularly for updates on
advisories that relate to your site.
-----------------------------------------------------------------------------
I. Description of IBM AIX vulnerability
A vulnerability exists in /bin/login on all IBM AIX 3 systems.
II. Impact of IBM AIX vulnerability
Remote users can obtain unauthorized root access on the affected
hosts.
III. Solution for IBM AIX vulnerability
IBM is working on an official fix, which is still under
development. The reference number for this fix is APAR IX44254.
Until you obtain the official fix from IBM, we encourage you to
apply the workaround or install the emergency fix below.
A. Workaround
The recommended workaround is to disable the rlogin daemon:
1. As root, edit /etc/inetd.conf
Comment out the line 'login ... rlogin'
2. Run 'inetimp'
3. Run 'refresh -s inetd'
B. Emergency fix
The emergency fix for the different levels of AIX 3
affected by this vulnerability is available via anonymous
FTP from software.watson.ibm.com:/pub/rlogin/rlogin.tar.Z.
Installation instructions are included in the README file
(which is included in rlogin.tar.Z).
Checksum information for rlogin.tar.Z:
BSD: 25285 317
SystemV: 13021 633 rlogin.tar.Z
MD5: MD5 (rlogin.tar.Z) = 803ee38c2e3b8c8c575e2ff5e921034c
C. Official fix
The official fix for this problem can be ordered as
APAR IX44254.
To order an APAR from IBM in the U.S., call 1-800-237-5511
and ask IBM to ship it as soon as it is available.
According to IBM, this fix will be available in
approximately two weeks. APARs may be obtained outside the
U.S. by contacting your local IBM representative.
IV. Description of Linux vulnerability
A vulnerability exists in /bin/login for Linux systems.
V. Impact of Linux vulnerability
Any user, remote or local, can obtain unauthorized root access on
the affected hosts.
VI. Solution for Linux vulnerability
A patch that addresses the remote access problem has been made
available via anonymous FTP from sunsite.unc.edu:
/pub/Linux/system/Network/sunacm/URGENT/README.security
/pub/Linux/system/Network/sunacm/URGENT/security.tgz
The "security.tgz" file includes other security fixes in addition
to the /bin/login patch.
Checksum information for README.security:
BSD: 09575 1
SystemV: 20945 1 README.security
MD5: MD5 (README.security) = 41d14d7b8725c7a1015adeb49601619b
Checksum information for security.tgz:
BSD: 32878 257
SystemV: 40797 513 security.tgz
MD5: MD5 (security.tgz) = dd4585cf4da1b52d25d619bf45f55b75
To address the local access problem, we encourage you to install
a version of /bin/login that does not allow the -f option in the
form "-f<user>", but only allows this option in the form
"-f <user>", as two arguments. At this time, we do not know
which versions of login.c are vulnerable. As we receive
additional information, we will update the CA-94:09.README file.
Again, we encourage you to check this README file regularly for
updates.
---------------------------------------------------------------------------
The CERT Coordination Center wishes to thank Axel Clauberg of
University of Cologne for reporting the IBM AIX problem, and
IBM for their assistance in responding to this problem.
---------------------------------------------------------------------------
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).
If you wish to send sensitive incident or vulnerability information to
CERT via electronic mail, CERT strongly advises that the e-mail be
encrypted. CERT can support a shared DES key, PGP (public key
available via anonymous FTP on info.cert.org), or PEM (contact CERT
for details).
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
USA
Past advisories and their associated README files, information about
FIRST representatives, and other information related to computer
security are available for anonymous FTP from info.cert.org.
-----------------------------------------------------------------------------
Appendix
CA-94:09.README
This file is a supplement to the CERT Advisory
CA-94:09.bin.login.vulnerability of May 23, 1994, and will be updated
as additional information becomes available.
We have received feedback from these vendors, who indicated that their
products are not vulnerable:
Amdahl
Apple
BSD
BSDI
Harris
HP
Motorola
NeXT
Pyramid
SCO
SGI
Solbourne
Sony
Sun
CERT has verified that the following vendor products are not vulnerable:
Free BSD
We have received feedback from these vendors, who have made patches
available to address the /bin/login vulnerability:
IBM
workaround: see Section III. Solution for IBM AIX
vulnerability A. Workaround of CERT advisory
CA-94:xx
emergency patch: software.watson.ibm.com:/pub/rlogin/rlogin.tar.Z
Official patch: APAR IX44254
Linux
patch: sunsite.unc.edu:/pub/Linux/system/Network/sunacm/URGENT/*
- - - - - - - - - - - - - - - - -
CA-94:09 CERT Advisory
May 23, 1994
/bin/login Vulnerability
-----------------------------------------------------------------------------
The CERT Coordination Center has learned of a vulnerability in
/bin/login. This vulnerability potentially affects all IBM AIX 3
systems and Linux systems. At this time, we believe that only
IBM AIX 3 and Linux systems are at risk.
Included with this advisory is an appendix containing the
CA-94:09.README, which lists the vendors who have responded to our
inquiries, and the status of their investigation into this
vulnerability report. As we receive additional information relating
to this advisory, we will place it, along with any clarifications, in
the README file, available via anonymous FTP from info.cert.org. We
encourage you to check the README files regularly for updates on
advisories that relate to your site.
-----------------------------------------------------------------------------
I. Description of IBM AIX vulnerability
A vulnerability exists in /bin/login on all IBM AIX 3 systems.
II. Impact of IBM AIX vulnerability
Remote users can obtain unauthorized root access on the affected
hosts.
III. Solution for IBM AIX vulnerability
IBM is working on an official fix, which is still under
development. The reference number for this fix is APAR IX44254.
Until you obtain the official fix from IBM, we encourage you to
apply the workaround or install the emergency fix below.
A. Workaround
The recommended workaround is to disable the rlogin daemon:
1. As root, edit /etc/inetd.conf
Comment out the line 'login ... rlogin'
2. Run 'inetimp'
3. Run 'refresh -s inetd'
B. Emergency fix
The emergency fix for the different levels of AIX 3
affected by this vulnerability is available via anonymous
FTP from software.watson.ibm.com:/pub/rlogin/rlogin.tar.Z.
Installation instructions are included in the README file
(which is included in rlogin.tar.Z).
Checksum information for rlogin.tar.Z:
BSD: 25285 317
SystemV: 13021 633 rlogin.tar.Z
MD5: MD5 (rlogin.tar.Z) = 803ee38c2e3b8c8c575e2ff5e921034c
C. Official fix
The official fix for this problem can be ordered as
APAR IX44254.
To order an APAR from IBM in the U.S., call 1-800-237-5511
and ask IBM to ship it as soon as it is available.
According to IBM, this fix will be available in
approximately two weeks. APARs may be obtained outside the
U.S. by contacting your local IBM representative.
IV. Description of Linux vulnerability
A vulnerability exists in /bin/login for Linux systems.
V. Impact of Linux vulnerability
Any user, remote or local, can obtain unauthorized root access on
the affected hosts.
VI. Solution for Linux vulnerability
A patch that addresses the remote access problem has been made
available via anonymous FTP from sunsite.unc.edu:
/pub/Linux/system/Network/sunacm/URGENT/README.security
/pub/Linux/system/Network/sunacm/URGENT/security.tgz
The "security.tgz" file includes other security fixes in addition
to the /bin/login patch.
Checksum information for README.security:
BSD: 09575 1
SystemV: 20945 1 README.security
MD5: MD5 (README.security) = 41d14d7b8725c7a1015adeb49601619b
Checksum information for security.tgz:
BSD: 32878 257
SystemV: 40797 513 security.tgz
MD5: MD5 (security.tgz) = dd4585cf4da1b52d25d619bf45f55b75
To address the local access problem, we encourage you to install
a version of /bin/login that does not allow the -f option in the
form "-f<user>", but only allows this option in the form
"-f <user>", as two arguments. At this time, we do not know
which versions of login.c are vulnerable. As we receive
additional information, we will update the CA-94:09.README file.
Again, we encourage you to check this README file regularly for
updates.
---------------------------------------------------------------------------
The CERT Coordination Center wishes to thank Axel Clauberg of
University of Cologne for reporting the IBM AIX problem, and
IBM for their assistance in responding to this problem.
---------------------------------------------------------------------------
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).
If you wish to send sensitive incident or vulnerability information to
CERT via electronic mail, CERT strongly advises that the e-mail be
encrypted. CERT can support a shared DES key, PGP (public key
available via anonymous FTP on info.cert.org), or PEM (contact CERT
for details).
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
USA
Past advisories and their associated README files, information about
FIRST representatives, and other information related to computer
security are available for anonymous FTP from info.cert.org.
-----------------------------------------------------------------------------
Appendix
CA-94:09.README
This file is a supplement to the CERT Advisory
CA-94:09.bin.login.vulnerability of May 23, 1994, and will be updated
as additional information becomes available.
We have received feedback from these vendors, who indicated that their
products are not vulnerable:
Amdahl
Apple
BSD
BSDI
Harris
HP
Motorola
NeXT
Pyramid
SCO
SGI
Solbourne
Sony
Sun
CERT has verified that the following vendor products are not vulnerable:
Free BSD
We have received feedback from these vendors, who have made patches
available to address the /bin/login vulnerability:
IBM
workaround: see Section III. Solution for IBM AIX
vulnerability A. Workaround of CERT advisory
CA-94:xx
emergency patch: software.watson.ibm.com:/pub/rlogin/rlogin.tar.Z
Official patch: APAR IX44254
Linux
patch: sunsite.unc.edu:/pub/Linux/system/Network/sunacm/URGENT/*
- - - - - - - - - - - - - - - - -