From: SecuriTeam <support@securiteam.com.>
To: [email protected]
Date: 23 Mar 2006 14:19:44 +0200
Subject: [UNIX] Sendmail Memory Leak DoS
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Sendmail Memory Leak DoS
------------------------------------------------------------------------
SUMMARY
<http://www.sendmail.com/>; sendmail is "a powerful, efficient, and
scalable Mail Transport Agent"
A memory leak in Sendmail allows attackers to DoS sendmail by exhausting
memory.
DETAILS
Vulnerable Systems:
* Sendmail version 8.13.5 and prior
* Sendmail version 8.12.10 and prior
Immune Systems:
* Sendmail version 8.13.6
The function sm_syslog at conf.c contain a memory leak.
The memory leak will cause with every be a usage of sm_syslog, allocation
of new memory that will never be released, until all available memory has
been exhausted.
Code Snips:
File conf.c line 5324:
/* VARARGS3 */
void
#ifdef __STDC__
sm_syslog(int level, const char *id, const char *fmt, ...)
#else /* __STDC__ */
sm_syslog(level, id, fmt, va_alist)
..
for (;;)
{
int n;
/* print log message into buf */
SM_VA_START(ap, fmt);
n = sm_vsnprintf(buf, bufsize, fmt, ap);
SM_VA_END(ap);
SM_ASSERT(n > 0);
if (n < bufsize)
break;
/* String too small, redo with correct size */
bufsize = n + 1;
if (buf != buf0)
{
sm_free(buf);
buf = NULL;
}
buf = sm_malloc_x(bufsize);
}
/* clean up buf after it has been expanded with args */
newstring = str2prt(buf);
if ((strlen(newstring) + idlen + 1) < SYSLOG_BUFSIZE)
{
..
if (buf == buf0)
buf = NULL; <- Memory leak
errno = save_errno;
return;
}
Vendor Status:
The vendor has issued a fix: <http://www.sendmail.org/8.13.6.html>;
http://www.sendmail.org/8.13.6.html
Patch for Sendmail version 8.13.5 available at:
<ftp://ftp.sendmail.org/pub/sendmail/8.13.5.p0>;
ftp://ftp.sendmail.org/pub/sendmail/8.13.5.p0
Patch for Sendmail version 8.12.11 available at:
<ftp://ftp.sendmail.org/pub/sendmail/8.12.11.p0>;
ftp://ftp.sendmail.org/pub/sendmail/8.12.11.p0
ADDITIONAL INFORMATION
The information has been provided by Ido Kanner (SecuriTeam).
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The information in this bulletin is provided "AS IS" without warranty of any kind.
In no event shall we be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages.
