Decompressing Snom Firmware
I (krzee) recently decided to check if Snom ever decided to update their version of OpenVPN yet. About 18 months ago I informed them on their forum  that their versions of openssl and openvpn are insecure. When I went to reply to my own post to bump it, I found that Snom has decided to discontinue their web forum, and their new helpdesk is closed to the public. They will only allow their authorized resellers to use their new helpdesk. So now I can no longer reach them to see if they care about my request at all. I decided it was time to decompress their latest vpn firmware in order to see what version of openvpn it contains. I found the exact same version (2.2.2) Hopefully next time one of us decompresses their VPN firmware we will find an up to date version of openvpn and openssl (or better, mbedtls). In case they remove the web forum all together, here was my post:
Posted 13 March 2015 - 11:02 AM by krzee on snom710-SIP 126.96.36.199: OpenSSL 1.0.0c 2 Dec 2010 OpenVPN 2.2.2 mips-linux [SSL] [LZO2] [EPOLL] [eurephia] http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-0224 https://community.openvpn.net/openvpn/wiki/CCSInjection http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-3567 https://community.openvpn.net/openvpn/wiki/VulnerabilitiesFixedInOpenSSL1.0.1j There is also a HMAC key leak in openvpn 2.3.0 and before. What are the plans for updating openssl and openvpn? that version of openssl is from 2010 and openvpn is from 2011!
I started with file, just in case I was looking at a zip/tar that they renamed .bin
> file snom760-vpnfeature-r.bin snom760-vpnfeature-r.bin: data
it's not a known file format, so next I tried binwalk. The version from apt-get gave me nothing, so i installed the latest git and it said:
> binwalk snom760-vpnfeature-r.bin DECIMAL HEXADECIMAL DESCRIPTION -------------------------------------------------------------------------------- 256 0x100 OpenSSL encryption, salted, salt: 0x-4BD2A526-583EEAB2
This let me know that I was going to need use a root console on an snom phone to pull out more info... The following is the commands (and contents of a file) that I used to decompress the files in the firmware package.
# Yes, that is 1024 :-p > cat firmware1.pub -----BEGIN PUBLIC KEY----- MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDpLolhDoYHzFJWkAG8IBS1xdM7 nloux+nWyB2sHdH3O+fzuXdzO7RSkflx/Yoa+GrFXPn1CMQMTiL7VScTU8d4wcvP U7RJ1LaDX9Xpg/H9Py1Sfwz12bEJtXigTi6dT2QS6CrOI8zAZluzQArsoiEyQzjq knHQIZiY+HLiiRNSTwIDAQAB -----END PUBLIC KEY----- keyFile=update.key pubFile=firmware1.pub imgFile=snom760-vpnfeature-r.bin dd if=$imgFile bs=128 skip=1 count=1 2>/dev/null | openssl rsautl -verify -out $keyFile -inkey "$pubFile" -pubin >/dev/null 2>&1 dd if=$imgFile bs=128 skip=2 2>/dev/null | openssl enc -aes128 -d -kfile $keyFile 2>/dev/null | tar --exclude=proc/.hidden --exclude=sys/.hidden -xzmf -