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__________________________________________________________
The U.S. Department of Energy
Computer Incident Advisory Capability
___ __ __ _ ___
/ | /_\ /
\___ __|__ / \ \___
__________________________________________________________
INFORMATION BULLETIN
Solaris 2.x Buffer Overflow Vulnerabilities (ps, chkey)
May 22, 1997 17:00 GMT Number H-59
______________________________________________________________________________
PROBLEM: Two buffer overflow vulnerabilities have been identified:
1) ps(1) program
2) chkey(1) program
PLATFORM: All platforms with Solaris 2.x
DAMAGE: These vulnerabilities may allow local users to gain root
privileges.
SOLUTION: Until patches are available, take the steps outlined in Section
3 of each advisory as soon as possible.
______________________________________________________________________________
VULNERABILITY Exploit details involving these vulnerabilities have been made
ASSESSMENT: publicly available.
______________________________________________________________________________
[ Start AUSCERT Advisories ]
1) ps(1) program
===========================================================================
AA-97.17 AUSCERT Advisory
Solaris 2.x ps Buffer Overflow Vulnerability
21 May 1997
Last Revised:
- -----------------------------------------------------------------------------
AUSCERT has received information that a vulnerability exists in the
ps(1) program under Solaris 2.x.
This vulnerability may allow local users to gain root privileges.
Exploit information involving this vulnerability has been made publicly
available.
Currently there are no vendor patches available that address this
vulnerability. AUSCERT recommends that sites take the steps outlined in
section 3 as soon as possible.
This advisory will be updated as more information becomes available.
- -----------------------------------------------------------------------------
1. Description
AUSCERT has received information that a vulnerability exists in the
Solaris 2.x ps(1) program.
ps is a program used to print information about active processes on
the system.
Due to insufficient bounds checking on arguments passed to the ps
program, it is possible to overwrite the internal data space of this
program while it is executing. This vulnerability may allow local
users to gain root privileges.
Exploit information involving this vulnerability has been made publicly
available.
Under Solaris 2.x there are two distinct vulnerable versions of ps.
These are installed by default in /usr/bin/ and /usr/ucb/.
Sun Microsystems is aware of this problem and is currently
investigating it.
2. Impact
Local users may gain root privileges.
3. Workarounds/Solution
AUSCERT recommends that sites limit the possible exploitation of this
vulnerability by immediately applying the workaround given in Section
3.1.
To maintain the functionality of ps, AUSCERT recommends applying the
workaround given in Section 3.2.
Currently there are no vendor patches available that address this
vulnerability. AUSCERT recommends that official vendor patches be
installed when they are made available.
3.1 Remove setuid and non-root execute permissions
To prevent the exploitation of the vulnerability described in this
advisory, AUSCERT recommends that the setuid permissions be removed
from ps program immediately. As the ps program will no longer work
for non-root users, it is recommended that the execute permissions
for them also be removed.
# ls -l /usr/bin/ps /usr/ucb/ps
-r-sr-xr-x 1 root sys 23752 Oct 25 1995 /usr/bin/ps
-rwsr-xr-x 1 root sys 23408 Oct 25 1995 /usr/ucb/ps
# chmod 500 /usr/bin/ps /usr/ucb/ps
# ls -l /usr/bin/ps /usr/ucb/ps
-r-x------ 1 root sys 23752 Oct 25 1995 /usr/bin/ps
-r-x------ 1 root sys 23408 Oct 25 1995 /usr/ucb/ps
3.2 Install wrapper
AUSCERT has developed a wrapper to help prevent programs from being
exploited using the vulnerability described in this advisory. Sites
which have a C compiler can obtain the source, compile and install
the wrapper as described in Section 3.2.1. For sites without a C
compiler, AUSCERT has made pre-compiled binaries available for Solaris
2.4, 2.5 and 2.5.1 (Section 3.2.2).
3.2.1 Installing the wrapper from source
The source for the wrapper, including installation instructions, can
be obtained from:
ftp://ftp.auscert.org.au/pub/auscert/tools/overflow_wrapper/
overflow_wrapper.c
This wrapper replaces the ps program and checks the length of the
command line arguments which are passed to it. If an argument exceeds
a certain predefined value (MAXARGLEN), the wrapper exits without
executing the ps command. The wrapper program can also be configured
to syslog any failed attempts to execute ps with arguments exceeding
MAXARGLEN. For further instructions on using this wrapper, please
read the comments at the top of overflow_wrapper.c.
The wrapper will need to be applied to both ps programs on the system
(/usr/bin/ps and /usr/ucb/ps).
When compiling overflow_wrapper.c for use with ps, AUSCERT recommends
defining MAXARGLEN to be 32.
The MD5 checksum for the current version of overflow_wrapper.c can be
retrieved from:
ftp://ftp.auscert.org.au/pub/auscert/tools/overflow_wrapper/CHECKSUM
The CHECKSUM file has been digitally signed using the AUSCERT PGP key.
3.2.2 Installing the wrapper binaries
Pre-compiled wrapper binaries are provided for sites that wish to
install the wrapper but do not have a C compiler available. AUSCERT
has compiled the wrapper on Solaris 2.4, 2.5 and 2.5.1. The following
compile time options have been used to the create the binaries:
REAL_PROG='"/usr/bin/ps.real"'
MAXARGLEN=32
SYSLOG
and
REAL_PROG='"/usr/ucb/ps.real"'
MAXARGLEN=32
SYSLOG
More information on these options can be found in Section 3.2.1 and
in the overflow_wrapper.c source code.
The pre-compiled binaries for the wrapper program can be retrieved
from:
ftp://ftp.auscert.org.au/pub/auscert/tools/ps_wrapper.tar.Z
The MD5 checksum for ps_wrapper.tar.Z is:
MD5 (ps_wrapper.tar.Z) = 6c0a9a2739561aba5968fc54b10d8c32
ps_wrapper.tar.Z contains a README file with installation instructions,
as well as pre-compiled binaries for /usr/bin/ps and /usr/ucb/ps under
Solaris 2.4, 2.5 and 2.5.1. The binaries have been linked statically
so they are larger than the default ps binary.
Sites are encouraged to carefully read the installation notes in the
README file before installation.
===========================================================================
2) chkey(1) program
===========================================================================
AA-97.18 AUSCERT Advisory
Solaris 2.x chkey Buffer Overflow Vulnerability
22 May 1997
Last Revised:
- -----------------------------------------------------------------------------
AUSCERT has received information that a vulnerability exists in the
chkey(1) program under Solaris 2.x.
This vulnerability may allow local users to gain root privileges.
Exploit information involving this vulnerability has been made publicly
available.
Currently there are no vendor patches available that address this
vulnerability. AUSCERT recommends that sites take the steps outlined in
section 3 as soon as possible.
This advisory will be updated as more information becomes available.
- -----------------------------------------------------------------------------
1. Description
AUSCERT has received information that a vulnerability exists in the
Solaris 2.x chkey(1) program.
chkey is used to change a user's secure RPC public key and secret key
pair.
Due to insufficient bounds checking on arguments passed to the chkey
program, it is possible to overwrite the internal data space of this
program while it is executing. As chkey has setuid root permissions,
this vulnerability may allow local users to gain root privileges.
Exploit information involving this vulnerability has been made publicly
available.
chkey under Solaris 2.x is located by default in /usr/bin/.
Sun Microsystems is aware of this problem and is currently
investigating it.
2. Impact
Local users may gain root privileges.
3. Workarounds/Solution
AUSCERT recommends that sites limit the possible exploitation of this
vulnerability by immediately applying the workaround given in Section
3.1.
To maintain the functionality of chkey, AUSCERT recommends applying
the workaround given in Section 3.2.
Currently there are no vendor patches available that address this
vulnerability. AUSCERT recommends that official vendor patches be
installed when they are made available.
3.1 Remove setuid and non-root execute permissions
To prevent the exploitation of the vulnerability described in this
advisory, AUSCERT recommends that the setuid permissions be removed
from the chkey program immediately. As the chkey program will no
longer work for non-root users, it is recommended that the execute
permissions for them also be removed.
# ls -l /usr/bin/chkey
-r-sr-xr-x 1 root sys 19608 Oct 25 1995 /usr/bin/chkey
# chmod 500 /usr/bin/chkey
# ls -l /usr/bin/chkey
-r-x------ 1 root sys 19608 Oct 25 1995 /usr/bin/chkey
For those sites which require the chkey functionality, AUSCERT
recommends applying the workaround given in Section 3.2.
3.2 Install wrapper
AUSCERT has developed a wrapper to help prevent programs from being
exploited using the vulnerability described in this advisory. Sites
which have a C compiler can obtain the source, compile and install
the wrapper as described in Section 3.2.1. For sites without a C
compiler, AUSCERT has made pre-compiled binaries available for Solaris
2.4, 2.5 and 2.5.1 (Section 3.2.2).
3.2.1 Installing the wrapper from source
The source for the wrapper, including installation instructions, can
be obtained from:
ftp://ftp.auscert.org.au/pub/auscert/tools/overflow_wrapper/
overflow_wrapper.c
This wrapper replaces the chkey program and checks the length of the
command line arguments which are passed to it. If an argument exceeds
a certain predefined value (MAXARGLEN), the wrapper exits without
executing the chkey command. The wrapper program can also be
configured to syslog any failed attempts to execute chkey with
arguments exceeding MAXARGLEN. For further instructions on using this
wrapper, please read the comments at the top of overflow_wrapper.c.
When compiling overflow_wrapper.c for use with chkey, AUSCERT recommends
defining MAXARGLEN to be 32.
The MD5 checksum for the current version of overflow_wrapper.c can be
retrieved from:
ftp://ftp.auscert.org.au/pub/auscert/tools/overflow_wrapper/CHECKSUM
The CHECKSUM file has been digitally signed using the AUSCERT PGP key.
3.2.2 Installing the wrapper binaries
Pre-compiled wrapper binaries are provided for sites that wish to
install the wrapper but do not have a C compiler available. AUSCERT
has compiled the wrapper on Solaris 2.4, 2.5 and 2.5.1. The following
compile time options have been used to the create the binaries:
REAL_PROG='"/usr/bin/chkey.real"'
MAXARGLEN=32
SYSLOG
More information on these options can be found in Section 3.2.1 and
in the overflow_wrapper.c source code.
The pre-compiled binaries for the wrapper program can be retrieved
from:
ftp://ftp.auscert.org.au/pub/auscert/tools/AA-97.18-chkey_wrapper.tar.Z
The MD5 checksum for AA-97.18-chkey_wrapper.tar.Z is:
MD5 (AA-97.18-chkey_wrapper.tar.Z) = bafd43c2357156595d65c7ed38fd6aeb
AA-97.18-chkey_wrapper.tar.Z contains a README file with installation
instructions, as well as pre-compiled binaries for /usr/bin/chkey
under Solaris 2.4, 2.5 and 2.5.1. The binaries have been linked
statically so they are larger than the default chkey binary.
Sites are encouraged to carefully read the installation notes in the
README file before installation.
===========================================================================
[ End AUSCERT Advisories ]
______________________________________________________________________________
CIAC wishes to acknowledge the contributions of AUSCERT and Nelson Marques
(The University of Queensland) for the information contained in this bulletin.
Thanks also to the Department of Mathematics(The University of Queensland) for
providing temporary test equipment.
______________________________________________________________________________
CIAC, the Computer Incident Advisory Capability, is the computer
security incident response team for the U.S. Department of Energy
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