Package: openssh-client
Version: 1:6.7p1-6
Severity: grave
Tags: security
ssh-keygen and ssh itself are using MD5 for fingerprints:
vauxhall ok % ssh-keygen -l -f ~/.ssh/id_rsa.pub
2048 9d:24:66:6e:37:8c:48:0f:28:1e:ba:36:b7:e3:47:e4 /home/bmc/.ssh/id_rsa.pub (RSA)
vauxhall ok % awk '{print $2}' ~/.ssh/id_rsa.pub| base64 -d | md5sum
9d24666e378c480f281eba36b7e347e4 -
MD5 is not suitable for any application requiring collision resistance,
such as a key fingerprint. Please switch to one of the SHA-2 values
instead, or upgrade to OpenSSH 6.8, which fixes this problem.
This is in fact a security vulnerability, since if the attacker
generates a valid RSA private key, they can generate an arbitrary e
(even if it is inefficient) and d, since they know p and q. As a
result, they have significant freedom to generate a key whose
fingerprint collides with another given key, and therefore perform an
MITM attack on first use. It is not a help that the length of the value
is prepended, since there are more than enough bits to allow any valid
length to be chosen.
-- System Information:
Debian Release: stretch/sid
APT prefers unstable
APT policy: (500, 'unstable'), (500, 'stable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386
Kernel: Linux 3.19.0-trunk-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
Versions of packages openssh-client depends on:
ii adduser 3.113+nmu3
ii dpkg 1.18.1
ii libc6 2.19-18
ii libedit2 3.1-20150325-1
ii libgssapi-krb5-2 1.12.1+dfsg-20
ii libselinux1 2.3-2
ii libssl1.0.0 1.0.2c-1
ii passwd 1:4.2-3
ii zlib1g 1:1.2.8.dfsg-2+b1
Versions of packages openssh-client recommends:
ii xauth 1:1.0.9-1
Versions of packages openssh-client suggests:
pn keychain <none>
pn libpam-ssh <none>
pn monkeysphere <none>
ii ssh-askpass-gnome [ssh-askpass] 1:6.7p1-6
-- no debconf information
--
brian m. carlson / brian with sandals: Houston, Texas, US
+1 832 623 2791 | http://www.crustytoothpaste.net/~bmc | My opinion only
OpenPGP: RSA v4 4096b: 88AC E9B2 9196 305B A994 7552 F1BA 225C 0223 B187
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