stunnel crashes with weak certificates... could it be OpenSSL?

Roger Cruz

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Feb 12, 2010, 1:36:51 PM2/12/10

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I posted the following message in the stunnel group. I’m following that posting here because I believe this may be an issue with the underlying library which is OpenSSL. Is there a known issue with certificates for version 0.9.8b that are aware of? What version of OpenSSL contains the fix if there is one?

Roger

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We ran Nessus on a Linux system and found that stunnel crashes when the weak certificate suite is enabled. GDB shows the stack trace below and it appears to be in the SSL library. My search on this mailing list led me to this message that appears to report a similar problem

http://mirt.net/pipermail/stunnel-users/2008-January/001830.html

Am I to understand that the problem is really with OpenSSL and that’s what needs to be upgraded? If so, do we know what version will have the fixed problem?

I’m going to post in the OpenSSL forum as well, but I wanted to start here since from our perspective, Stunnel is the one crashing.

Thank you

Roger Cruz

2010.02.05 12:49:11 LOG7[13524:3086718672]: Cleaning up the signal pipe

2010.02.05 12:49:11 LOG6[13524:3086718672]: Child process 13575 finished with code 0

Program received signal SIGSEGV, Segmentation fault.

[Switching to Thread 0xb7fa7b90 (LWP 13574)]

0x007b24a7 in krb5_is_referral_realm () from /usr/lib/libkrb5.so.3

(gdb) bt

#0 0x007b24a7 in krb5_is_referral_realm () from /usr/lib/libkrb5.so.3

#1 0x0089d338 in kssl_keytab_is_available () from /lib/libssl.so.6

#2 0x008803b1 in ssl3_choose_cipher () from /lib/libssl.so.6

#3 0x0087b2a2 in ssl3_get_client_hello () from /lib/libssl.so.6

#4 0x0087bc85 in ssl3_accept () from /lib/libssl.so.6

#5 0x0089109a in SSL_accept () from /lib/libssl.so.6

#6 0x00884d0d in ssl23_get_client_hello () from /lib/libssl.so.6

#7 0x0088554b in ssl23_accept () from /lib/libssl.so.6

#8 0x0089109a in SSL_accept () from /lib/libssl.so.6

#9 0x003628e2 in ?? () from /usr/sbin/stunnel

#10 0x00363acd in ?? () from /usr/sbin/stunnel

#11 0x003645ba in ?? () from /usr/sbin/stunnel

#12 0x003646a8 in client () from /usr/sbin/stunnel

#13 0x0025f45b in start_thread () from /lib/libpthread.so.0

#14 0x00448e5e in clone () from /lib/libc.so.6

(gdb) quit

[root@p20xen1 current_hq]# stunnel -version

stunnel 4.15 on i686-redhat-linux-gnu with OpenSSL 0.9.8b 04 May 2006

Threading:PTHREAD SSL:ENGINE Sockets:POLL,IPv6 Auth:LIBWRAP

Global options

debug = 5

pid = /var/run/stunnel.pid

RNDbytes = 64

RNDfile = /dev/urandom

RNDoverwrite = yes

Service-level options

cert = /etc/stunnel/stunnel.pem

ciphers = ALL:!ADH:+RC4:@STRENGTH

key = /etc/stunnel/stunnel.pem

session = 300 seconds

TIMEOUTbusy = 300 seconds

TIMEOUTclose = 60 seconds

TIMEOUTconnect = 10 seconds

TIMEOUTidle = 43200 seconds

verify = none

Thomas J. Hruska

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Feb 12, 2010, 3:04:01 PM2/12/10

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Roger Cruz wrote:
> I posted the following message in the stunnel group. I'm following that
> posting here because I believe this may be an issue with the underlying
> library which is OpenSSL. Is there a known issue with certificates for
> version 0.9.8b that are aware of? What version of OpenSSL contains the
> fix if there is one?
>
>
>
> Roger

0.9.8b is ancient (almost 4 years old). There have been many security
updates and patches since then. Current release is 0.9.8l (with a beta
of 0.9.8m also available). Try updating OpenSSL first to 0.9.8l.

--
Thomas Hruska
Shining Light Productions

Home of BMP2AVI, Nuclear Vision, ProtoNova, and Win32 OpenSSL.
http://www.slproweb.com/

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Victor Duchovni

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Feb 12, 2010, 4:20:12 PM2/12/10

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On Fri, Feb 12, 2010 at 01:04:01PM -0700, Thomas J. Hruska wrote:

> Roger Cruz wrote:
>> I posted the following message in the stunnel group. I'm following that
>> posting here because I believe this may be an issue with the underlying
>> library which is OpenSSL. Is there a known issue with certificates for
>> version 0.9.8b that are aware of? What version of OpenSSL contains the
>> fix if there is one?
>> Roger
>
> 0.9.8b is ancient (almost 4 years old). There have been many security
> updates and patches since then. Current release is 0.9.8l (with a beta of
> 0.9.8m also available). Try updating OpenSSL first to 0.9.8l.

Also, the reported crash was in the Kerberos library, and it is unwise
to attempt to enable the Kerberos ciphers, they are obsolete and insecure
(single DES). If the Kerberos ciphers are off by default, the OP should
not enable them.

--
Viktor.