5486625 2000-09-18 22:12 /125 rader/ Brevbäraren (som är implementerad i) Python
Mottagare: Bugtraq (import) <12841>
Ärende: [RHSA-2000:061-02] syslog format vulnerability in klogd
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From: bugzilla@REDHAT.COM
To: BUGTRAQ@SECURITYFOCUS.COM
Message-ID: <200009181942.PAA16899@lacrosse.corp.redhat.com>
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Red Hat, Inc. Security Advisory
Synopsis: syslog format vulnerability in klogd
Advisory ID: RHSA-2000:061-02
Issue date: 2000-09-18
Updated on: 2000-09-18
Product: Red Hat Linux
Keywords: syslog format string klogd syslogd
Cross references: N/A
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1. Topic:
Various vulnerabilities exist in syslogd/klogd. By exploiting these
vulnerabilities, it could be possible for local users to gain root
access. No remote exploit exists at this time, but it remains
theoretically possible that this vulnerability could be exploited
remotely under certain rare circumstances.
All users should upgrade to the new sysklogd packages. Users of
Red Hat Linux 6.0 and 6.1 should use the packages for Red Hat
Linux 6.2.
2. Relevant releases/architectures:
Red Hat Linux 5.2 - i386, alpha, sparc
Red Hat Linux 6.0 - i386, alpha, sparc
Red Hat Linux 6.1 - i386, alpha, sparc
Red Hat Linux 6.2 - i386, alpha, sparc
3. Problem description:
klogd contains instances of the:
syslog( LOG_INFO, buffer ); vulnerability that has been recently
been discussed on Bugtraq and similar mailing lists; by supplying
some string that contains '%' escapes, it is possible to have those
escapes interpreted, which can lead to the ability to gain root
access.
Also, there are a couple of minor buffer overflow/termination
problems that could allow local users to crash syslogd and cause
bogus messages to be printed on the local system console.
The updated sysklogd packages fix these vulnerabilities/issues.
4. Solution:
For each RPM for your particular architecture, run:
rpm -Fvh [filename]
where filename is the name of the RPM.
5. Bug IDs fixed (http://bugzilla.redhat.com/bugzilla for more info):
N/A
6. RPMs required:
Red Hat Linux 5.2:
sparc:
ftp://updates.redhat.com/5.2/sparc/sysklogd-1.3.31-1.6.sparc.rpm
alpha:
ftp://updates.redhat.com/5.2/alpha/sysklogd-1.3.31-1.6.alpha.rpm
i386:
ftp://updates.redhat.com/5.2/i386/sysklogd-1.3.31-1.6.i386.rpm
sources:
ftp://updates.redhat.com/5.2/SRPMS/sysklogd-1.3.31-1.6.src.rpm
Red Hat Linux 6.2:
sparc:
ftp://updates.redhat.com/6.2/sparc/sysklogd-1.3.31-17.sparc.rpm
i386:
ftp://updates.redhat.com/6.2/i386/sysklogd-1.3.31-17.i386.rpm
alpha:
ftp://updates.redhat.com/6.2/alpha/sysklogd-1.3.31-17.alpha.rpm
sources:
ftp://updates.redhat.com/6.2/SRPMS/sysklogd-1.3.31-17.src.rpm
7. Verification:
MD5 sum Package Name
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cd92613fc9a7409a90f6ff774e6e85d7 5.2/SRPMS/sysklogd-1.3.31-1.6.src.rpm
c7c44b7a38f4518daecca77cf7d45ba8 5.2/alpha/sysklogd-1.3.31-1.6.alpha.rpm
f100359030451c4be9b3bd99c3ec73a1 5.2/i386/sysklogd-1.3.31-1.6.i386.rpm
1c7f004ca29c966e0a03896f239d1317 5.2/sparc/sysklogd-1.3.31-1.6.sparc.rpm
69d50a8a9d490598fc11eef40fdf4552 6.2/SRPMS/sysklogd-1.3.31-17.src.rpm
2a7e2c7848d1f2d9607f3e6e3702cf2e 6.2/alpha/sysklogd-1.3.31-17.alpha.rpm
287d5022aa9d1a6ba9e03c51acc85229 6.2/i386/sysklogd-1.3.31-17.i386.rpm
150a05567dd4d626326028b1ac31f34d 6.2/sparc/sysklogd-1.3.31-17.sparc.rpm
These packages are GPG signed by Red Hat, Inc. for security. Our key
is available at:
http://www.redhat.com/corp/contact.html
You can verify each package with the following command:
rpm --checksig <filename>
If you only wish to verify that each package has not been corrupted or
tampered with, examine only the md5sum with the following command:
rpm --checksig --nogpg <filename>
8. References:
Thanks go to Jouko Pynnonen, Solar Designer, and Daniel Jacobowitz
for discovering the vulnerabilities and providing patches.
Copyright(c) 2000 Red Hat, Inc.
(5486625) ------------------------------------------(Ombruten)
5490493 2000-09-19 21:58 /195 rader/ Brevbäraren (som är implementerad i) Python
Mottagare: Bugtraq (import) <12854>
Kommentar till text 5486625 av Brevbäraren (som är implementerad i) Python
Ärende: Re: [RHSA-2000:061-02] syslog format vulnerability in klogd
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From: Solar Designer <solar@FALSE.COM>
To: BUGTRAQ@SECURITYFOCUS.COM
Message-ID: <200009190506.JAA03061@false.com>
> Various vulnerabilities exist in syslogd/klogd. By exploiting these
> vulnerabilities, it could be possible for local users to gain root
> access. No remote exploit exists at this time, but it remains
> theoretically possible that this vulnerability could be exploited
> remotely under certain rare circumstances.
The Linux vendor updates and sysklogd 1.4 should be fixing three
kinds of vulnerabilities:
1. klogd "format bugs" found by Jouko Pynnönen. (Note that the
"obvious" fix for this would break the decoding of priorities.)
2. A Linux/sysklogd-specific syslogd bug reported to Debian and fixed
by Daniel Jacobowitz:
"There was a silly logic error in printchopped() that caused it to
zero out the wrong portion of the buffer, leaving a message of "<",
which had priority 0. That caused a kern.emerg log, which is by
default walled to all users. Oops."
see http://bugs.debian.org/32580 for the full story.
3. Two syslogd printline() bugs found by me, see below.
Patches for just these security bugs can be obtained here:
ftp://ftp.openwall.com/pvt/sysklogd-1.3-31-security-patches.tar.gz
The printline() problems are not specific to the sysklogd package.
Fortunately, they're relatively minor.
Below are some quotes from the message I sent to the vendor-sec list,
*BSD security contacts, and the major commercial Unix vendors.
(Is there an e-mail security contact for SCO?)
| This is to report several bugs found in the printline() function in
| implementations of syslogd derived from Eric Allman's.
|
| I don't know if all of the vendors I'm sending this to are affected.
| Please, treat this as an opportunity to check your operating system
| for this kind of problems.
Some of the vendors have replied (even though I didn't explicitly ask
for a reply), so I'll summarize the responses I've got:
Jeff Polk of BSDI replied saying that "BSDI fixed this in the BSD/OS
tree in May of 1996. No supported releases of BSD/OS are vulnerable."
Compaq has replied that the problem "has not been found to affect the
as shipped, Compaq Tru64/UNIX Operating Systems Software".
SGI replied that they've filed a bug id and are investigating IRIX.
[...]
| Below is information on the (free) operating systems that I was able
| to check:
|
| * OpenBSD, NetBSD, FreeBSD-stable, CORE-SDI's ssyslog 1.22:
|
| Two bugs in printline():
|
| 1. Single-byte buffer overflow (may be caused to write a NUL beyond
| the end of line[]).
|
| 2. Will truncate lines at the first '\200' character.
OpenBSD and NetBSD have now fixed the bugs.
CORE-SDI's new msyslog v1.0 has the buffer overflow fixed, but not
the '\200' bug, yet.
The '\200' bug may allow an attacker to partially avoid logging in
certain cases, such as with a syslog(3) call like this:
syslog(LOG_INFO, "%s of %s tried to login as %s",
remote_user, remote_host, target_user);
| * sysklogd 1.3-31, as used on most current Linux distributions:
|
| Two bugs in printline():
|
| 1. Single-byte buffer overflow.
|
| 2. Does not escape control characters '\177' through '\237'.
These have now been fixed.
| * FreeBSD-current:
|
| One bug in printline(), which results in:
|
| 1. Single-byte buffer overflow (which was fixed and re-introduced
| with the new bug).
|
| 2. Control characters '\200' through '\237' are escaped differently
| than intended (as a sequence of 4 characters rather than 3).
|
| In addition to this, the ctype macros used in some implementations of
| printline() may produce undefined results for 8-bit characters on some
| older platforms (with non-ANSI C libraries).
|
| Fortunately, the buffer overflow is very likely non-exploitable. The
| line[] buffer is declared to be 1025 bytes large (this is MAXLINE + 1)
| and other variables local to the function are either unimportant or
| require at least a 32-bit alignment. Thus, in my testing line[1025]
| was pointing to unused stack space needed to achieve the alignment.
| Of course, a compiler may not guarantee to align the buffer itself
| (it is only the integer and pointer variables that are guaranteed to
| be aligned on most, but not all, platforms), in which case it may be
| placed right below one of the other variables allowing for attacks.
|
| Finally, the proposed patch for printline(), as found in the sysklogd
| package. The patch may easily be ported to other syslogd clones. It
| is important to pay attention to the variable declarations: "c" should
| be an "unsigned char".
diff -rU 27 sysklogd-1.3-31.orig/syslogd.c sysklogd-1.3-31/syslogd.c
--- sysklogd-1.3-31.orig/syslogd.c Tue Jan 19 14:31:58 1999
+++ sysklogd-1.3-31/syslogd.c Wed Sep 13 00:45:55 2000
@@ -1419,60 +1419,65 @@
void printline(hname, msg)
const char *hname;
char *msg;
{
register char *p, *q;
register unsigned char c;
char line[MAXLINE + 1];
int pri;
/* test for special codes */
pri = DEFUPRI;
p = msg;
if (*p == '<') {
pri = 0;
while (isdigit(*++p))
{
pri = 10 * pri + (*p - '0');
}
if (*p == '>')
++p;
}
if (pri &~ (LOG_FACMASK|LOG_PRIMASK))
pri = DEFUPRI;
memset (line, 0, sizeof(line));
q = line;
- while ((c = *p++) && q < &line[sizeof(line) - 1]) {
+ while ((c = *p++) && q < &line[sizeof(line) - 4]) {
if (c == '\n')
*q++ = ' ';
- else if (iscntrl(c)&&(c<0177)) {
+ else if (c < 040) {
*q++ = '^';
*q++ = c ^ 0100;
+ } else if (c == 0177 || (c & 0177) < 040) {
+ *q++ = '\\';
+ *q++ = '0' + ((c & 0300) >> 6);
+ *q++ = '0' + ((c & 0070) >> 3);
+ *q++ = '0' + (c & 0007);
} else
*q++ = c;
}
*q = '\0';
logmsg(pri, line, hname, SYNC_FILE);
return;
}
/*
* Take a raw input line from /dev/klog, split and format similar to syslog().
*/
void printsys(msg)
char *msg;
{
register char *p, *q;
register int c;
char line[MAXLINE + 1];
int pri, flags;
char *lp;
(void) snprintf(line, sizeof(line), "vmunix: ");
lp = line + strlen(line);
for (p = msg; *p != '\0'; ) {
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