__________________________________________________________
The U.S. Department of Energy
Computer Incident Advisory Capability
___ __ __ _ ___
/ | /_\ /
\___ __|__ / \ \___
__________________________________________________________
INFORMATION BULLETIN
Vulnerability in suidperl (sperl)
April 8, 1998 21:00 GMT Number H-66a
______________________________________________________________________________
PROBLEM: A problem has been identified in suidperl that allows a buffer
overflow condition.
PLATFORM: All Unix systems with Perl 4.x and Perl 5.x.
DAMAGE: When calling this program with appropriately crafted
parameters, unauthorized local users can execute arbitrary
commands as root.
SOLUTION: Apply the proper patch supply by vendor.
______________________________________________________________________________
VULNERABILITY This vulnerability is being actively exploited.
ASSESSMENT:
______________________________________________________________________________
[ Appended on April 8, 1998 with additional vendor information ]
[ Start CERT Advisory ]
=============================================================================
CERT* Advisory CA-97.17
Original issue date: May 29, 1997
Last revised: --
Topic: Vulnerability in suidperl (sperl)
- ------------------------------------------------------------------------------
The CERT Coordination Center has received reports of a buffer overflow
condition in suidperl built from Perl 4.n and Perl 5.n distributions on UNIX
systems. By calling this program with appropriately crafted parameters,
unauthorized local users can execute arbitrary commands as root. This
vulnerability is being actively exploited.
The CERT/CC team recommends installing a vendor patch if one is available (see
Section III.B). Until you can do so, we recommend disabling suidperl (Section
III.A). Two other alternatives are to install suidperl or sperl from version
5.003 source code along with the patch provided in Appendix B of this
advisory (see also Section III.C), or upgrade to Perl version 5.004 (Section
III.D). Note that Perl4 is no longer supported.
We will update this advisory as we receive additional information.
Please check our advisory files regularly for updates that relate to your
site.
- ------------------------------------------------------------------------------
I. Description
On some systems, setuid and setgid scripts (scripts written in the C
shell, Bourne shell, or Perl, for example, with the set user or group ID
permissions enabled) are insecure due to a race condition in the
kernel. For those systems, Perl versions 4 and 5 attempt to work around
this vulnerability with a special program named suidperl, also known as
sperl. This program attempts to emulate the set-user-ID and set-group-ID
features of the kernel.
There is a buffer overflow condition in suidperl built from Perl 4.n and
Perl 5.n distributions earlier than version 5.004. If this program is
called with appropriately crafted parameters, an attacker can execute
arbitrary commands as root. This vulnerability is being actively
exploited.
II. Impact
Users executing Perl scripts with the setuid bit set can execute
arbitrary commands with the effective uid of the owner of the Perl
script. Attackers can execute commands as root.
III. Solution
Use the command in Section A to help you determine if your system is
vulnerable and, if it is, to (optionally) disable the suidperl and sperl
programs (see Section A). If you find that your system is vulnerable,
replace the suidperl and sperl programs with new versions.
Section B describes how to do that if your site uses versions of suidperl
and sperl that are provided as part of a vendor-supplied distribution.
Sites that installed suidperl and sperl programs themselves from the Perl
source distribution should patch the distribution as described in Section
C or upgrade to version 5.004 as described in Section D. Note that Perl4
is no longer supported.
A. Determine if your system is vulnerable and disable vulnerable programs
To determine if a system is vulnerable to this problem and to disable
the programs that are believed to be vulnerable, use the following
find command or a variant. Consult your local system documentation to
determine how to tailor the find program on your system.
After you have run this command on all your systems, they will no
longer be vulnerable. Note that after disabling the suidperl and sperl
programs, they will no longer be able to emulate the set-user-ID and
set-group-ID features of the kernel.
You will need to run the find command on each system you maintain
because the command examines files on the local disk only. Substitute
the names of your local file systems for FILE_SYSTEM_NAMES in the
example. Example local file system names are /, /usr, and /var.
You must do this as root.
Note that this is one long command, though we have separated
it onto five lines using back-slashes.
find FILE_SYSTEM_NAMES -xdev -type f -user root \
\( -name 'sperl4.[0-9][0-9][0-9]' \
-o -name 'sperl5.00[0-3]' \
-o -name 'suidperl' \) \
-perm -04000 -print -ok chmod ug-s '{}' \;
This command will find all files on a system that are
- only in the file system you name (FILE_SYSTEM_NAMES -xdev)
- regular files (-type f)
- owned by root (-user root)
- named appropriately (-name 'sperl4.[0-9][0-9][0-9]'
-o -name 'sperl5.00[0-3]'
-o -name 'suidperl')
- setuid root (-perm -04000)
Once found, those files will
- have their names printed (-print)
- have their modes changed, but only if you type `y'
in response to the prompt (-ok chown ug-s '{}' \;)
B. Obtain and install the appropriate patch from your vendor
If your vendor ships suidperl or sperl, you may be vulnerable and need
a patch. Appendix A contains information provided by the following
vendors. If your vendor is not on this list, please contact the vendor
directly.
Berkeley Software Design, Inc. (BSDI)
Cray Research - A Silicon Graphics Company
Data General Corporation
Hewlett-Packard Company
IBM Corporation
Linux
The Santa Cruz Operation, Inc. (SCO)
Silicon Graphics, Inc. (SGI)
Until you can install a patch, we recommend disabling suidperl.
The find command above will help you do that. If you need
suidperl or sperl, see the alternatives in Sections C and D below.
C. Install suidperl or sperl from 5.003 source code and apply a patch.
Follow the instructions below, which were provided by Chip Salzenberg.
If you would like to keep using setuid Perl scripts, fix Perl
yourself by following these steps:
1. Go to your Perl 5.003 source directory, or else obtain a fresh
Perl 5.003 distribution from
http://www.perl.com/CPAN/src/5.0/perl5.003.tar.gz
or another CPAN archive accessible to you.
This file is approximately 1.5 megabytes in size.
2. Using the "patch" program, apply the patch that is enclosed
below in Appendix B.
3. Build and install the patched Perl 5.003. (If you have never
built Perl before, be sure to read the "INSTALL" file first.)
Perl 5.003 binaries that have had this patch applied, and therefore
are safe from all known attacks, can be identified by the
output of the "perl -v" command: the "locally applied patches" list
will include "SUIDBUF - Buffer overflow fixes for suidperl
security".
D. Install suidperl or sperl from 5.004 source code (no patch needed).
If you would like to upgrade to Perl version 5.004, follow these
steps:
1. Obtain a fresh Perl 5.004 distribution from
http://www.perl.com/CPAN/src/5.0/perl5.004.tar.gz
or another CPAN archive accessible to you.
This file is approximately 2.5 megabytes in size.
2. Build and install Perl 5.004 according to the instructions
given in the "INSTALL" file. Do NOT apply the patch.
Perl 5.004 binaries, which are safe from all known attacks, can be
identified by the output of the "perl -v" command: it should say
"This is perl, version 5.004". (Unlike the 5.003 patch mentioned
in Section C, the "locally applied patches" list will NOT include
"SUIDBUF - Buffer overflow fixes for suidperl security". The fact
that it is version 5.004 is sufficient in this case.)
==============================================================================
Appendix A - Vendor Information
Below is a list of the vendors who have provided information for this
advisory. We will update this appendix as we receive additional information.
If you do not see your vendor's name, the CERT/CC did not hear from that
vendor. Please contact the vendor directly.
Berkeley Software Design, Inc. (BSDI)
=====================================
BSD/OS is vulnerable to the suidperl (sperl) buffer overflow problem. We
will be releasing a patch for BSDI 3.0 and perl 5.003 and are currently
working on patches for BSD/OS 3.0 and Perl 4.036. We will also be developing
patches for the perl versions shipped with BSD/OS 2.1.
Cray Research - A Silicon Graphics Company
==========================================
Cray Research does not ship perl as part of either Unicos or Unicos/mk.
Data General Corporation
========================
The only perl executables that are shipped with DG/UX are:
/bin/perl
and
/bin/perl5 /* in R420 */
These are not set uid programs.
Therefore,
No versions of DG/UX are vulnerable to this problem.
Hewlett-Packard Company
=======================
HP does not ship this product.
IBM Corporation
===============
AIX versions do not have Perl as part of the standard product.
However, the SP2's PSSP software does contain suidperl, but the
program is not installed with the setuid bit set.
IBM and AIX are registered trademarks of International Business Machines
Corporation.
Linux
=====
Red Hat 4.2 is not vulnerable
Red Hat 4.1/4.0 you can get the upgraded RPM from ftp.redhat.com
If you wish to check whether you have the fixed perl run perl -v and
check for
Locally applied patches:
SUIDBUF - Buffer overflow fixes for suidperl security
The Santa Cruz Operation, Inc. (SCO)
====================================
suidperl is not included in any SCO products.
SCO CMW+ and SCO OpenServer do not have kernel support for setuid
scripts, but you may have installed suidperl in order to emulate
that functionality - in that case you should replace your version of
perl with version 5.004, or patch your source code as noted in this
advisory.
SCO UnixWare does have safe kernel support for setuid scripts so
that suidperl is not necessary. If you have installed a version
of perl that includes suidperl, you should remove suidperl and
install a version of perl built so as not to require it.
Silicon Graphics, Inc. (SGI)
=============================
At this time, Silicon Graphics does not have any public information for
this suidperl/sperl issue. Silicon Graphics has communicated with
CERT and other external security parties and is actively investigating
this issue. When more Silicon Graphics information (including any
possible patches) is available for release, that information will
be released via the SGI security mailing list, wiretap.
For subscribing to the wiretap mailing list and other SGI security
related information, please refer to the Silicon Graphics Security
Headquarters website located at:
http://www.sgi.com/Support/Secur/security.html
============================================================================
Appendix B - Source Code Patch Information
The following patch information has been supplied by Chip Salzenberg. If you
built suidperl or sperl from 5.003 source code, we encouraged you to apply
this patch (see the explanation in Section III.C above).
Patch follows.
- ---------------------------------------------------------------------------
Index: patchlevel.h
***************
*** 41,42 ****
- - --- 41,43 ----
+ ,"SUIDBUF - Buffer overflow fixes for suidperl security"
,NULL
};
Index: perl.c
*************** char *s;
*** 1212,1216 ****
# endif
#endif
! fputs("\n\t+ suidperl security patch", stdout);
fputs("\n\nCopyright 1987-1996, Larry Wall\n",stdout);
#ifdef MSDOS
- - --- 1212,1216 ----
# endif
#endif
! fputs("\n\t+ two suidperl security patches", stdout);
fputs("\n\nCopyright 1987-1996, Larry Wall\n",stdout);
#ifdef MSDOS
Index: gv.c
*************** gv_fetchfile(name)
*** 59,67 ****
char *name;
{
! char tmpbuf[1200];
GV *gv;
! sprintf(tmpbuf,"::_<%s", name);
gv = gv_fetchpv(tmpbuf, TRUE, SVt_PVGV);
sv_setpv(GvSV(gv), name);
if (*name == '/' && (instr(name,"/lib/") || instr(name,".pm")))
- - --- 59,80 ----
char *name;
{
! char smallbuf[256];
! char *tmpbuf;
! STRLEN tmplen;
GV *gv;
! tmplen = strlen(name) + 4;
! if (tmplen < sizeof smallbuf)
! tmpbuf = smallbuf;
! else
! New(603, tmpbuf, tmplen + 1, char);
! tmpbuf[0] = ':';
! tmpbuf[1] = ':';
! tmpbuf[2] = '_';
! tmpbuf[3] = '<';
! strcpy(tmpbuf + 4, name);
gv = gv_fetchpv(tmpbuf, TRUE, SVt_PVGV);
+ if (tmpbuf != smallbuf)
+ Safefree(tmpbuf);
sv_setpv(GvSV(gv), name);
if (*name == '/' && (instr(name,"/lib/") || instr(name,".pm")))
Index: toke.c
*************** static char *scan_const _((char *start))
*** 22,26 ****
static char *scan_formline _((char *s));
static char *scan_heredoc _((char *s));
! static char *scan_ident _((char *s, char *send, char *dest, I32 ck_uni));
static char *scan_inputsymbol _((char *start));
static char *scan_pat _((char *start));
- - --- 22,27 ----
static char *scan_formline _((char *s));
static char *scan_heredoc _((char *s));
! static char *scan_ident _((char *s, char *send, char *dest, STRLEN destlen,
! I32 ck_uni));
static char *scan_inputsymbol _((char *start));
static char *scan_pat _((char *start));
*************** static char *scan_str _((char *start));
*** 28,32 ****
static char *scan_subst _((char *start));
static char *scan_trans _((char *start));
! static char *scan_word _((char *s, char *dest, int allow_package, STRLEN
*slp));
static char *skipspace _((char *s));
static void checkcomma _((char *s, char *name, char *what));
- - --- 29,34 ----
static char *scan_subst _((char *start));
static char *scan_trans _((char *start));
! static char *scan_word _((char *s, char *dest, STRLEN destlen,
! int allow_package, STRLEN *slp));
static char *skipspace _((char *s));
static void checkcomma _((char *s, char *name, char *what));
*************** static char * filter_gets _((SV *sv, FIL
*** 47,50 ****
- - --- 49,54 ----
static void restore_rsfp _((void *f));
+ static char too_long[] = "Identifier too long";
+
/* The following are arranged oddly so that the guard on the switch
statement
* can get by with a single comparison (if the compiler is smart enough).
*************** int allow_tick;
*** 475,479 ****
(allow_tick && *s == '\'') )
{
! s = scan_word(s, tokenbuf, allow_pack, &len);
if (check_keyword && keyword(tokenbuf, len))
return start;
- - --- 479,483 ----
(allow_tick && *s == '\'') )
{
! s = scan_word(s, tokenbuf, sizeof tokenbuf, allow_pack, &len);
if (check_keyword && keyword(tokenbuf, len))
return start;
*************** register char *s;
*** 847,851 ****
unsigned char un_char = 0, last_un_char;
char *send = strchr(s,']');
! char tmpbuf[512];
if (!send) /* has to be an expression */
- - --- 851,855 ----
unsigned char un_char = 0, last_un_char;
char *send = strchr(s,']');
! char tmpbuf[sizeof tokenbuf * 4];
if (!send) /* has to be an expression */
*************** register char *s;
*** 872,876 ****
weight -= seen[un_char] * 10;
if (isALNUM(s[1])) {
! scan_ident(s,send,tmpbuf,FALSE);
if ((int)strlen(tmpbuf) > 1 && gv_fetchpv(tmpbuf,FALSE,
SVt_PV))
weight -= 100;
- - --- 876,880 ----
weight -= seen[un_char] * 10;
if (isALNUM(s[1])) {
! scan_ident(s, send, tmpbuf, sizeof tmpbuf, FALSE);
if ((int)strlen(tmpbuf) > 1 && gv_fetchpv(tmpbuf,FALSE,
SVt_PV))
weight -= 100;
*************** GV *gv;
*** 942,946 ****
{
char *s = start + (*start == '$');
! char tmpbuf[1024];
STRLEN len;
GV* indirgv;
- - --- 946,950 ----
{
char *s = start + (*start == '$');
! char tmpbuf[sizeof tokenbuf];
STRLEN len;
GV* indirgv;
*************** GV *gv;
*** 952,956 ****
gv = 0;
}
! s = scan_word(s, tmpbuf, TRUE, &len);
if (*start == '$') {
if (gv || last_lop_op == OP_PRINT || isUPPER(*tokenbuf))
- - --- 956,960 ----
gv = 0;
}
! s = scan_word(s, tmpbuf, sizeof tmpbuf, TRUE, &len);
if (*start == '$') {
if (gv || last_lop_op == OP_PRINT || isUPPER(*tokenbuf))
*************** yylex()
*** 1629,1633 ****
case '*':
if (expect != XOPERATOR) {
! s = scan_ident(s, bufend, tokenbuf, TRUE);
expect = XOPERATOR;
force_ident(tokenbuf, '*');
- - --- 1633,1637 ----
case '*':
if (expect != XOPERATOR) {
! s = scan_ident(s, bufend, tokenbuf, sizeof tokenbuf, TRUE);
expect = XOPERATOR;
force_ident(tokenbuf, '*');
*************** yylex()
*** 1645,1649 ****
case '%':
if (expect != XOPERATOR) {
! s = scan_ident(s, bufend, tokenbuf + 1, TRUE);
if (tokenbuf[1]) {
expect = XOPERATOR;
- - --- 1649,1653 ----
case '%':
if (expect != XOPERATOR) {
! s = scan_ident(s, bufend, tokenbuf + 1, sizeof tokenbuf - 1, TRUE);
if (tokenbuf[1]) {
expect = XOPERATOR;
*************** yylex()
*** 1748,1752 ****
s++;
if (s < bufend && isALPHA(*s)) {
! d = scan_word(s, tokenbuf, FALSE, &len);
while (d < bufend && (*d == ' ' || *d == '\t'))
d++;
- - --- 1752,1756 ----
s++;
if (s < bufend && isALPHA(*s)) {
! d = scan_word(s, tokenbuf, sizeof tokenbuf, FALSE, &len);
while (d < bufend && (*d == ' ' || *d == '\t'))
d++;
*************** yylex()
*** 1847,1851 ****
}
! s = scan_ident(s-1, bufend, tokenbuf, TRUE);
if (*tokenbuf) {
expect = XOPERATOR;
- - --- 1851,1855 ----
}
! s = scan_ident(s - 1, bufend, tokenbuf, sizeof tokenbuf, TRUE);
if (*tokenbuf) {
expect = XOPERATOR;
*************** yylex()
*** 1956,1960 ****
case '$':
if (s[1] == '#' && (isALPHA(s[2]) || strchr("_{$:", s[2]))) {
! s = scan_ident(s+1, bufend, tokenbuf+1, FALSE);
if (expect == XOPERATOR) {
if (lex_formbrack && lex_brackets == lex_formbrack) {
- - --- 1960,1965 ----
case '$':
if (s[1] == '#' && (isALPHA(s[2]) || strchr("_{$:", s[2]))) {
! s = scan_ident(s + 1, bufend, tokenbuf + 1, sizeof tokenbuf - 1,
! FALSE);
if (expect == XOPERATOR) {
if (lex_formbrack && lex_brackets == lex_formbrack) {
*************** yylex()
*** 1982,1986 ****
TOKEN(DOLSHARP);
}
! s = scan_ident(s, bufend, tokenbuf+1, FALSE);
if (expect == XOPERATOR) {
if (lex_formbrack && lex_brackets == lex_formbrack) {
- - --- 1987,1991 ----
TOKEN(DOLSHARP);
}
! s = scan_ident(s, bufend, tokenbuf + 1, sizeof tokenbuf - 1, FALSE);
if (expect == XOPERATOR) {
if (lex_formbrack && lex_brackets == lex_formbrack) {
*************** yylex()
*** 2016,2024 ****
if (*s == '{' && strEQ(tokenbuf, "$SIG") &&
(t = strchr(s,'}')) && (t = strchr(t,'='))) {
! char tmpbuf[1024];
STRLEN len;
for (t++; isSPACE(*t); t++) ;
if (isIDFIRST(*t)) {
! t = scan_word(t, tmpbuf, TRUE, &len);
if (*t != '(' && perl_get_cv(tmpbuf, FALSE))
warn("You need to quote \"%s\"", tmpbuf);
- - --- 2021,2029 ----
if (*s == '{' && strEQ(tokenbuf, "$SIG") &&
(t = strchr(s,'}')) && (t = strchr(t,'='))) {
! char tmpbuf[sizeof tokenbuf];
STRLEN len;
for (t++; isSPACE(*t); t++) ;
if (isIDFIRST(*t)) {
! t = scan_word(t, tmpbuf, sizeof tmpbuf, TRUE, &len);
if (*t != '(' && perl_get_cv(tmpbuf, FALSE))
warn("You need to quote \"%s\"", tmpbuf);
*************** yylex()
*** 2093,2097 ****
case '@':
! s = scan_ident(s, bufend, tokenbuf+1, FALSE);
if (expect == XOPERATOR)
no_op("Array",s);
- - --- 2098,2102 ----
case '@':
! s = scan_ident(s, bufend, tokenbuf + 1, sizeof tokenbuf - 1, FALSE);
if (expect == XOPERATOR)
no_op("Array",s);
*************** yylex()
*** 2129,2133 ****
: !GvHV(gv) )))
{
! char tmpbuf[1024];
sprintf(tmpbuf, "Literal @%s now requires backslash",tokenbuf+1);
yyerror(tmpbuf);
- - --- 2134,2138 ----
: !GvHV(gv) )))
{
! char tmpbuf[sizeof tokenbuf + 40];
sprintf(tmpbuf, "Literal @%s now requires backslash",tokenbuf+1);
yyerror(tmpbuf);
*************** yylex()
*** 2293,2297 ****
keylookup:
bufptr = s;
! s = scan_word(s, tokenbuf, FALSE, &len);
if (*s == ':' && s[1] == ':' && strNE(tokenbuf, "CORE"))
- - --- 2298,2302 ----
keylookup:
bufptr = s;
! s = scan_word(s, tokenbuf, sizeof tokenbuf, FALSE, &len);
if (*s == ':' && s[1] == ':' && strNE(tokenbuf, "CORE"))
*************** yylex()
*** 2338,2342 ****
if (*s == '\'' || *s == ':' && s[1] == ':') {
! s = scan_word(s, tokenbuf + len, TRUE, &len);
if (!len)
croak("Bad name after %s::", tokenbuf);
- - --- 2343,2348 ----
if (*s == '\'' || *s == ':' && s[1] == ':') {
! s = scan_word(s, tokenbuf + len, sizeof tokenbuf - len,
! TRUE, &len);
if (!len)
croak("Bad name after %s::", tokenbuf);
*************** yylex()
*** 2557,2561 ****
s += 2;
d = s;
! s = scan_word(s, tokenbuf, FALSE, &len);
tmp = keyword(tokenbuf, len);
if (tmp < 0)
- - --- 2563,2567 ----
s += 2;
d = s;
! s = scan_word(s, tokenbuf, sizeof tokenbuf, FALSE, &len);
tmp = keyword(tokenbuf, len);
if (tmp < 0)
*************** yylex()
*** 3244,3250 ****
if (isIDFIRST(*s) || *s == '\'' || *s == ':') {
! char tmpbuf[128];
expect = XBLOCK;
! d = scan_word(s, tmpbuf, TRUE, &len);
if (strchr(tmpbuf, ':'))
sv_setpv(subname, tmpbuf);
- - --- 3250,3256 ----
if (isIDFIRST(*s) || *s == '\'' || *s == ':') {
! char tmpbuf[sizeof tokenbuf];
expect = XBLOCK;
! d = scan_word(s, tmpbuf, sizeof tmpbuf, TRUE, &len);
if (strchr(tmpbuf, ':'))
sv_setpv(subname, tmpbuf);
*************** char *what;
*** 4091,4102 ****
static char *
! scan_word(s, dest, allow_package, slp)
register char *s;
char *dest;
int allow_package;
STRLEN *slp;
{
register char *d = dest;
for (;;) {
if (isALNUM(*s))
*d++ = *s++;
- - --- 4097,4112 ----
static char *
! scan_word(s, dest, destlen, allow_package, slp)
register char *s;
char *dest;
+ STRLEN destlen;
int allow_package;
STRLEN *slp;
{
register char *d = dest;
+ register char *e = d + destlen - 3; /* two-character token, ending NUL
*/
for (;;) {
+ if (d >= e)
+ croak(too_long);
if (isALNUM(*s))
*d++ = *s++;
*************** STRLEN *slp;
*** 4119,4129 ****
static char *
! scan_ident(s,send,dest,ck_uni)
register char *s;
register char *send;
char *dest;
I32 ck_uni;
{
register char *d;
char *bracket = 0;
char funny = *s++;
- - --- 4129,4141 ----
static char *
! scan_ident(s, send, dest, destlen, ck_uni)
register char *s;
register char *send;
char *dest;
+ STRLEN destlen;
I32 ck_uni;
{
register char *d;
+ register char *e;
char *bracket = 0;
char funny = *s++;
*************** I32 ck_uni;
*** 4134,4143 ****
s = skipspace(s);
d = dest;
if (isDIGIT(*s)) {
! while (isDIGIT(*s))
*d++ = *s++;
}
else {
for (;;) {
if (isALNUM(*s))
*d++ = *s++;
- - --- 4146,4161 ----
s = skipspace(s);
d = dest;
+ e = d + destlen - 3; /* two-character token, ending NUL */
if (isDIGIT(*s)) {
! while (isDIGIT(*s)) {
! if (d >= e)
! croak(too_long);
*d++ = *s++;
+ }
}
else {
for (;;) {
+ if (d >= e)
+ croak(too_long);
if (isALNUM(*s))
*d++ = *s++;
- ---------------------------------------------------------------------------
End of patch.
- ------------------------------------------------------------------------------
[ End CERT Advisory ]
[ Append Silicon Graphic Inc. Advisory ]
-----BEGIN PGP SIGNED MESSAGE-----
______________________________________________________________________________
Silicon Graphics Inc. Security Advisory
Title: Buffer Overflow Vulnerability in suidperl/sperl program
Title: CERT CA-97.17 and AUSCERT AA-97.13
Number: 19980404-01-I
Date: April 6, 1998
______________________________________________________________________________
Silicon Graphics provides this information freely to the SGI user community
for its consideration, interpretation, implementation and use. Silicon
Graphics recommends that this information be acted upon as soon as possible.
Silicon Graphics provides the information in this Security Advisory on
an "AS-IS" basis only, and disclaims all warranties with respect thereto,
express, implied or otherwise, including, without limitation, any warranty
of merchantability or fitness for a particular purpose. In no event shall
Silicon Graphics be liable for any loss of profits, loss of business, loss
of data or for any indirect, special, exemplary, incidental or consequential
damages of any kind arising from your use of, failure to use or improper
use of any of the instructions or information in this Security Advisory.
______________________________________________________________________________
- -----------------------
- --- Issue Specifics ---
- -----------------------
The suidperl or sperl program is an altered versions of PERL which allows
PERL scripts to be run under the setuid of a particular user.
Unfortunately, a buffer overrun has been discovered in the suidperl/sperl
program which could allow arbitrary commands to be run as the
privileged user root.
Silicon Graphics Inc. has investigated the issue and recommends the
following steps for neutralizing the exposure. It is HIGHLY RECOMMENDED
that these measures be implemented on ALL vulnerable SGI systems.
- --------------
- --- Impact ---
- --------------
As a service to its customers, Silicon Graphics provides IRIX installable
inst images of many popular "free" software packages and can be found
on the SGI Freeware 1.0/2.0 CD or online at:
http://www.sgi.com/TasteOfDT/public/freeware.html
The suidperl/sperl program is freeware and is not installed by default.
Versions 5.003 and lower of suidperl/sperl have this buffer overrun
vulnerability.
With a local account, the suidperl/sperl buffer overrun vulnerability can be
exploited locally and remotely.
The suidperl/sperl buffer overrun vulnerability can be utilized to execute
commands with root privileges.
The suidperl/sperl buffer overrun vulnerability has been publicly discussed
in Usenet newsgroups and mailing lists and also reported in CERT Advisory
CA-97.17 and AUSCERT Advisory AA-97.13.
- --------------------------
- --- Temporary Solution ---
- --------------------------
Although new releases of suidperl/sperl are available to fix this issue, it
is realized that there may be situations where installing the new release
immediately may not be possible.
To determine if a system is vulnerable to this problem and to disable
the programs that are believed to be vulnerable, use the following steps.
1) Become the root user on the system.
% /bin/su -
Password:
#
2) Find suidperl or sperl programs and disable them.
You will need to run the find(1) command on each system you
maintain because the command examines files on local disks only.
Note that this is one long command, though we have separated it
onto five lines using backslashes.
# find / -local -type f -user root \
\( -name 'sperl4.[0-9][0-9][0-9]' \
-o -name 'sperl5.00[0-3]' \
-o -name 'suidperl' \) \
-perm -04000 -print -ok chmod ug-s '{}' \;
This command will find all files on a system that are
- only in the file system you name (/ -local)
- regular files (-type f)
- owned by root (-user root)
- named appropriately (-name 'sperl4.[0-9][0-9][0-9]' -o -name
'sperl5.00[0-3]' -o -name 'suidperl')
- setuid root (-perm -04000)
Once found, those files will
- have their names printed (-print)
- have their modes changed, but only if you type `y' in response
to the prompt (-ok chmod ug-s '{}' \;)
After you have run this command on all your systems, they will no
longer be vulnerable. Note that after disabling the suidperl and sperl
programs, they will no longer be able to emulate the set-user-ID and
set-group-ID features of the kernel.
3) Return to previous level.
# exit
$
- ----------------
- --- Solution ---
- ----------------
No Silicon Graphic's patches are available for freeware software.
As freeware software, all reasonable efforts will be made to address
the issue in future releases of the Silicon Graphic's Freeware.
Unsupported patches are publicly available from http://www.perl.com/
- ------------------------
- --- Acknowledgments ---
- ------------------------
Silicon Graphics wishes to thank the Internet Community, CERT Coordination
Center, and AUSCERT for their assistance in this matter.
- -----------------------------------------------------------
- --- Silicon Graphics Inc. Security Information/Contacts ---
- -----------------------------------------------------------
If there are questions about this document, email can be sent to
cse-security-alert@sgi.com.
------oOo------
Silicon Graphics provides security information and patches for
use by the entire SGI community. This information is freely
available to any person needing the information and is available
via anonymous FTP and the Web.
The primary SGI anonymous FTP site for security information and patches
is sgigate.sgi.com (204.94.209.1). Security information and patches
are located under the directories ~ftp/security and ~ftp/patches,
respectively. The Silicon Graphics Security Headquarters Web page is
accessible at the URL http://www.sgi.com/Support/security/security.html.
For issues with the patches on the FTP sites, email can be sent to
cse-security-alert@sgi.com.
For assistance obtaining or working with security patches, please
contact your SGI support provider.
------oOo------
Silicon Graphics provides a free security mailing list service
called wiretap and encourages interested parties to self-subscribe
to receive (via email) all SGI Security Advisories when they are
released. Subscribing to the mailing list can be done via the Web
(http://www.sgi.com/Support/security/wiretap.html) or by sending email
to SGI as outlined below.
% mail wiretap-request@sgi.com
subscribe wiretap <YourEmailAddress>
end
^d
In the example above, <YourEmailAddress> is the email address that you
wish the mailing list information sent to. The word end must be on a
separate line to indicate the end of the body of the message. The
control-d (^d) is used to indicate to the mail program that you are
finished composing the mail message.
------oOo------
Silicon Graphics provides a comprehensive customer World Wide Web site.
This site is located at http://www.sgi.com/Support/security/security.html.
------oOo------
For reporting *NEW* SGI security issues, email can be sent to
security-alert@sgi.com or contact your SGI support provider. A
support contract is not required for submitting a security report.
______________________________________________________________________________
This information is provided freely to all interested parties and may
be redistributed provided that it is not altered in any way, Silicon
Graphics is appropriately credited and the document retains and
includes its valid PGP signature.
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[ End Silicon Graphic Inc. Advisory ]
______________________________________________________________________________
CIAC wishes to acknowledge the contributions of CERT, Chip Salzenberg, Larry
Wall, and Warner Losh for the information contained in this bulletin.
______________________________________________________________________________
CIAC, the Computer Incident Advisory Capability, is the computer
security incident response team for the U.S. Department of Energy
(DOE) and the emergency backup response team for the National
Institutes of Health (NIH). CIAC is located at the Lawrence Livermore
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For emergencies and off-hour assistance, DOE, DOE contractor sites,
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