Is OpenVPN using "--tls-auth" vulnerable to CVE-2016-2107?

SecureOrNotSecure

Hi All,

I'm running an OpenVPN server with an OpenSSL version which is vulnerable to CVE-2016-2107 https://www.openssl.org/news/secadv/20160503.txt -> i.e. variant of a padding oracle attac.

However, I'm using the "--tls-auth"-feature.

Does this feature protect my OpenVPN connections with respect to CVE-2016-2107?

Moreover, I found a comment in the source of an older version on sourceforge. It says:

https://sourceforge.net/p/openvpn/openvpn-testing/ci/66407e11c4746e564bd4285e9c1a1805ecfd82bd/tree/doc/openvpn.8?diff=5f5229e41d134b659e502bb2597c711aedaf8096

-OpenVPN's usage of HMAC is to first encrypt a packet, then HMAC the resulting ciphertext.
+The OpenVPN data channel protocol uses encrypt-then-mac (i.e. first encrypt a
+packet, then HMAC the resulting ciphertext), which prevents padding oracle
+attacks.

So is OpenVPN resistent agains padding oracle attacs at all?

Thank you in advance
SONS

SecureOrNotSecure

Hmm, no response after one week :-(.

Is that the wrong place for such questions? Where else?
Is the question too silly and everybody knows the answer except me?
Does nobody care about it expect me. Neither the developers, the team nor the other forum users?

Kind Regards
SoNS

jonathanhle

If you dpkg the current openvpn_as server you can see it's updated for openssl past the bug:
jonathan@Jonathan-Les-MacBook-Pro:~/Downloads/openvpn/usr/local/openvpn_as/lib/pkgconfig$ cat openssl.pc
prefix=/usr/local/openvpn_as
exec_prefix=$
{prefix}
libdir=${exec_prefix}/lib64
includedir=${prefix}
/include
Name: OpenSSL
Description: Secure Sockets Layer and cryptography libraries and tools
Version: 1.0.2h
Requires: libssl libcrypto

For CVE-2016-2107 in https://www.openssl.org/news/secadv/20160503.txt:
"OpenSSL 1.0.2 users should upgrade to 1.0.2h"

We upgraded to the latest and are A-OK now: http://swupdate.openvpn.org/as/openvpn-as-2.1.0-Ubuntu14.amd_64.deb (as of this posting date for Ubuntu).