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------------------------------------- LLEGUE HASTA AQUI -------------------------------------------


== OpenSSH (Client) ==
See also [http://www.debian.org/security/key-rollover/#openssh Official Key-Rollover page].

You will need to have a list of the openssh keys that you currently have and where they have been copied to. For each key that is vulnerable:
== OpenSSH (Cliente) ==
Ver también [http://www.debian.org/security/key-rollover/#openssh Official Key-Rollover page].

Debe tener una lista de las llaves openssh que actualmente tiene y a donde han sido copiadas. Para cada llave que sea vulnerable:
Line 243: Line 240:
Replacing {{{rsa}}} by {{{dsa}}} if you prefer dsa keys and replacing {{{filename}}} and {{{hostname}}} with appropriate values.

Also remember to remove compromised keys from your .ssh/authorized_keys file!
Reemplazando {{{rsa}}} por {{{dsa}}} si prefiere llaves ds y reemplazando {{{filename}}} y {{{hostname}}} con los valores apropiados.

También recuerde remover las llaves comprometidas de su archivo .ssh/authorized_keys!
Line 248: Line 245:
Openswan's raw RSA key generation is not vulnerable, as it does not use the openssl library.
This means all connections using authby=rsasigkey are not vulnerable.

X.509 based keys generated by administrators for use with IPsec could be vulnerable if created
on a Debian system using the openssl command (as per documentation)

See [http://www.debian.org/security/key-rollover/#openswan Official Key-Rollover page].
La generación cruda de RSA no es vulnerable, y no usa la librería openssl.

Esto quiere decir que todas las conexiones que usen authby=rsasigkey no son vulnerables.

Las llaves basadas en X.509 por administradores para ser usadas con IPsec pueden ser vulnerables si fueron creadas en un sistema Debian usando el comando openssl (según la documentación).

Ver [http://www.debian.org/security/key-rollover/#openswan Official Key-Rollover page].
Line 257: Line 254:
See [http://www.debian.org/security/key-rollover/#openswan Official Key-Rollover page]. Ver [http://www.debian.org/security/key-rollover/#openswan Official Key-Rollover page].
Line 260: Line 257:
See [http://www.debian.org/security/key-rollover/#openvpn Official Key-Rollover page].

If you're using x509 certificates, you need to create a whole new CA if you generated the CA key with a broken OpenSSL. Even if you CA key isn't compromised, some of the keys of the OpenVPN clients might be. In that case you need to revoke all the certificates for those keys and add the CRL to your OpenVPN configuration. See the [http://openvpn.net/index.php/documentation/howto.html#revoke OpenVPN HOWTO] for more information about revocation.
Ver [http://www.debian.org/security/key-rollover/#openvpn Official Key-Rollover page].

Si está usando certificados x509, debe crear un CA completo si usted generó la llave CA con un OpenSSL roto. Incluso, si su llave CA no está comprometida, algunas de las llaves de los clientes OpenVPN pueden estarlo. En ese caso deberá revocar todos los certificados para esas llaves y añadir el CRL a la configuración de su OpenVPN. Ver [http://openvpn.net/index.php/documentation/howto.html#revoke OpenVPN HOWTO] para mayor información sobre la revocación.
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Generate a new PEM as shown in "Generic PEM Generation" above (making sure that it is placed in the correct place according to your postfix configuration, then restart postfix: {{{ invoke-rc.d postfix restart }}}. Genere un nuevo PEM como está descrito en "Generic PEM Generation" arriba (asegurándose que es colocado en el sitio correcto según la configuración particular, y luego reinicie Postfix: {{{ invoke-rc.d postfix restart }}}.
Line 268: Line 265:
See [http://www.debian.org/security/key-rollover/#puppet Official Key-Rollover page]. Ver [http://www.debian.org/security/key-rollover/#puppet Official Key-Rollover page].
Line 271: Line 268:
See [http://www.debian.org/security/key-rollover/#ssl-cert Official Key-Rollover page]. Ver [http://www.debian.org/security/key-rollover/#ssl-cert Official Key-Rollover page].
Line 274: Line 271:
See [http://www.debian.org/security/key-rollover/#telnetd-ssl Official Key-Rollover page]. Ver [http://www.debian.org/security/key-rollover/#telnetd-ssl Official Key-Rollover page].
Line 277: Line 274:
See [http://www.debian.org/security/key-rollover/#tinc Official Key-Rollover page]. Ver [http://www.debian.org/security/key-rollover/#tinc Official Key-Rollover page].
Line 280: Line 277:
See [http://www.debian.org/security/key-rollover/#tor Official Key-Rollover page].
Ver [http://www.debian.org/security/key-rollover/#tor Official Key-Rollover page].
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Analysis of the impact is still ongoing. Details known so far: encfs uses the RNG from libssl to create an internal encryption key with some post-processing applied. Checking of that key against a pre-calculated blacklist like with dowkd.pl might be possible when it's ready.

In the meantime, encrypted filesystems that might be created with a broken version of libssl shall be considered vulnerable against offline attacks. Any copy of encrypted data located in unthrusted environment might become readable, sooner or later. If the date of creation is unknown, checking of the originating version in output of the encfsctl command against the changelog of encfs package may provide some hints but is not absolutely reliable either because there was no strong dependency on certain openssl version.

To regain security, try following:

 * Create another encfs file system with encfs after upgrading to the latest (fixed) openssl library
 * Mount the original FS and copy the data into the new location
 * Umount the old filesystem. Destroy the contents of the old encrypted files using the shred command. (If the files have been moved rather than copied than make sure that the remaining space on the particular block device or filesystem is rewritten with random data).
Análisis del impacto aún está siendo determinado. Detalles al momento incluyen: enfs usa RNG de libssl para crear una llave de encriptación interna con un poco de post-procesmiento aplicado. La revisión de esa llave contra una pre-calculada en una lista negra como se hace con dowkd.pl puede ser posible cuando esté listo.

Mientras tanto, los sistemas de archivo encriptados que pudieron haber sido creados usando la versión rota de libssl, deben ser considerados vulnerables contra ataques fuera de línea. Cualquier copia de datos localizados en un ambiente no-confiable podrá ser legible tarde o temprano. Si la fecha de creación es desconocida, se puede revisar la versión originadora en la salida del comando encfsctl contra el changelog del paquete encfs, y esto puede proveer algunas pistas, aunque no es absolutamente confiable porque no habían dependencias fuertes en algunas versiones particulares de openssl.

Para garantizar la seguridad, pruebe lo siguiente:

 * Cree otro sistema de archivo con enfs luego de actualizar a la última versión del openssl corregido.
 * Monte el sistema de archivos original y copie la data a la nueva ubicación.
 * Desmonte el sistema de archivos viejo y destruya toda la data con shred.
Line 296: Line 293:
See [http://www.debian.org/security/key-rollover/#xrdp Official Key-Rollover page]. Ver [http://www.debian.org/security/key-rollover/#xrdp Official Key-Rollover page].

--------------------------------------- LLEGUE HASTA AQUI --------------------------------------

/!\ Esta página no es más que una traducción rápida y de emergencia de: http://wiki.debian.org/SSLkeys . Por favor ir a esa página para obtener la información más actualizada de este tema. . No creo poder mantener esto así que sería bueno si la gente toma la iniciativa de verificar el sitio original en inglés y actualiza esta acorde. Adicionalmente, donde no he podido encontrar traducción posible o sencillamente no entiendo, estoy colocando AYUDA DE UN EXPERTO para que por favor colaboren con sus aclaratorias.


  • ?TableOfContents

En el enlace [http://www.debian.org/security/2008/dsa-1571 Debian Security Advisory 1571] (New openssl packages fix predictable random number generator), el equipo de seguridad de Debian (Debian Security Team) reveló una vulnerabilidad en el paquete openssl que hace que muchas de las claves criptográficas que son utilizadas para autenticación (ej. a través de SSH) o firmado (ej. certificados digitales de servidores web) sean potencialmente vulnerables.

Sumario para el Usuario Final

The scope of the problem includes: El alcance de este problema incluye:

  • llaves débiles tanto para servidores como para clientes (ver sección "Identificando Llaves Débiles Abajo")
  • todos los tipos de llaves generadas usando openssl (esto incluye llaves RSA y DSA)
  • compromiso de otras llaves o claves que hayan sido transmitidas sobre un enlace encriptado que fuese establecido usando las llaves débiles. Nota que este último punto significa que claves transmitidas sobre ssh a un servidor con una llave DSA débil de servidor pudiese estar comprometida también; ver [http://lists.debian.org/debian-devel-announce/2008/05/msg00003.html la reacción del proyecto Debian a esto].

Las siguientes herramientas criptográficas NO se ven afectadas:

  • cryptsetup (ni LUKS ni el común dm-crypt use openssl, el openssl keyscript - que no es usado en las instalaciones por omisión - si usa openssl, pero solo para encriptar la llave, no para generar la llave que es usada para encriptar la partición; quiere decir que la encriptación de la clave puede ser menos fuerte que lo esperado pero la llave como tal, no)

  • GNUTLS
  • GnuPG

Identificando Llaves Débiles

Características de llaves potencialmente vulnerables:

  • Generadas desde 2006-09-17
  • Generadas con Etch, Lenny o Sid (Sarge no es vulnerable)
  • Generadas usando 'openssl', 'ssh-keygen', o 'openvpn --keygen' (GnuPG y GNUTLS no están afectadas)

Adicionalmente cualquier llave DSA debe ser considerada comprometida si ha sido utilizada en una máquina con un OpenSSL 'malo'. Simplemente usando una llave DSA 'fuerte' (generada con un OpenSSL 'bueno') para hacer una conexión desde una máquina que pudo haberse comprometido. Esto es debido a un 'ataque' sobre DSA que permite encontrar la llave privada si el nonce usado en la firma es conocido o reutilizado.

AYUDA DE UN EXPERTO: Por favor aclarar nonce arriba:

De Wikipedia: http://en.wiktionary.org/wiki/nonce nonce (plural nonces) 1. (cryptography) A datum constructed so as to be unique to a particular message in a stream, in order to prevent replay attacks.

Listas negras de llaves vulnerables en unstable:

  • openssh-blacklist
  • openssh-blacklist-extra
  • openssl-blacklist
  • openvpn-blacklist

Muchas listas de claves 'débiles' fueron generadas por el proyecto metasploit: http://metasploit.com/users/hdm/tools/debian-openssl/

Aplicaciones/protocolos que se saben que usan estas llaves:

  • OpenSSH (llaves tanto de servidores como de usuarios)
  • OpenVPN
  • Openswan
  • StrongSWAN
  • DNSSEC
  • Material de llaves para X.509
  • encfs
  • Tor
  • postfix, exim4, sendmail y otros MTAs usando SSL/TLS
  • cyrus imapd
  • courier imap/pop3
  • uw-imapd
  • dovecot con soporte imaps/pops
  • apache2 (ssl certs, ver "Llaves PEM" abajo)
  • dropbear
  • cfengine
  • puppet
  • xrdp
  • tinc
  • gitosis
  • vsftpd SSL certificados para FTPS
  • proftpd SSL/TLS certificados para FTPS
  • ftpd-ssl SSL certificados para FTPS
  • telnetd-ssl SSL certificados para SSL-Telnet
  • ?DomainKeys (DK) y DKIM

Parra arreglar esto, primero aptitude update && aptitude upgrade para instalar la nueva versión de los paquetes openssl y libssl0.9.8 (la vulnerabilidad está corregida en la versión 0.9.8c-4etch3 para etch y 0.9.8g-9 para lenny/sid). Probablemente querrás recoger los nuevos paquetes openssh que incluyen una lista negra de llaves débiles conocidas, pero vas a tener que aptitude dist-upgrade para poder acceder al nuevo paquete openssh-blacklist.

Si escoges no usar el método aptitude descrito arriba, debes notas que los siguientes paquetes deben ser actualizados (todos vienen del mismo paquete fuente):

  • openssl
  • libssl0.9.8
  • libssl-dev

Luego, debes regenrar y distribuir cualquier llave potencialmente vulnerable. Las instrucciones para regenerar las llaves para estas aplicaciones están abajo. También puedes probar para determinar si las llaves son vulnerables usando el utilitario dowkd.pl descrito m;as abajo.

¿Qué tan Débil?

La versión rota de OpenSSL estaba siendo semillada solamente por el número de proceso (PID). Dadas las diferencias entre las terminaciones (endianness) y el tamaño del entero grande (sizeof(long)), el resultado es dependiente de la arquitectura: little-endian 32bit (i386, o arquitecturas en las cuales los bits menos significativos están al final), little-endian 64bit (amd64, ia64), big-endian 32bit (powerpc, sparc o arquitecturas donde los bits más significativos están al final). El PID 0 es el kernel y PID_MAX (32768) no se usa en el vuelco, así que solo hubo 32767 flujos de números aleatorios por arquitectura. Esto es (2^15-1)*3 o 98301.

El OpenSSL que no está roto se semilla tanto del PID como de /dev/urandom.

Detalles por Aplicación Afectada

Asterisk

Asterisk usa llaves RSA como método opcional de autenticación para IAX2 y DUNDI. Estas llaves son pares público/privado. El paquete Asterisk no genera estas llaves automáticamente y la mayoría de los usuarios parecen no usarlas. Usted probablemente sabe si está usando una llave de estas.

BIND9

Para regenerar su llave rndc, haga lo siguientes. (Esto es lo que hace el script de postinst)

rndc-confgen -r /dev/urandom -a

> (comentario original de la página en inglés) No sé si esto es realmente necesario... ronalde: Según [http://packages.debian.org/changelogs/pool/main/b/bind9/bind9_9.4.2-10/changelog the changelog for bind9 in Debian] rndc-confgen en Debian usa /dev/urandom desde Marzo 2002 (incluso antes /dev/random era usado); Me imagino que las llaves rndc-keys no se ven afectadas.

Las llaves para DNSSEC o DynamicDNS son probablemente débiles y también deben ser regeneradas a través del uso de dnssec-keygen(1). Exactamente cuales parámetros deben usar depende de cómo está usando las llaves actualmente. Ver [http://www.ops.ietf.org/dns/dynupd/secure-ddns-howto.html Secure DDNS Howto] para algunos ejemplos con DDNS.

boxbackup

Ver [http://www.debian.org/security/key-rollover/#boxbackup Official Key-Rollover page].

Cfengine

Para cada nodo cfengine, remover las llaves viejas y generar las llaves nuevas:

rm /var/lib/cfengine2/ppkeys/localhost.priv
rm /var/lib/cfengine2/ppkeys/localhost.pub
/usr/sbin/cfkey
Then restart cfservd:
/etc/init.d/cfengine2 restart

Una vez que las llaves son generadas, intercambie las llaves entre los nodos para reestablecer la confianza en 2 vías.

courier imap/pop3

Follow the "Generic PEM Generation" instructions and add a openssl gendh >> mysite.pem. Siga las instrucciones "Generic PEM Generation" y añada un openssl gendh >> mysite.pem.

o

rm /etc/courier/imapd.pem
dpkg-reconfigure courier-imap-ssl

y deje que dpkg regenere un archivo imapd.pem

uw-imapd

Deje que dpkg genere de vuelta un archivo imapd.pem

cd /etc/ssl/certs
rm `openssl x509 -noout -hash < imapd.pem`.0
rm imapd.pem
dpkg-reconfigure uw-imapd

cryptsetup

Ver [http://www.debian.org/security/key-rollover/#cryptsetup Official Key-Rollover page].

csync2

Tal y como está descrito en /usr/share/doc/csync2/README.Debian

/etc/csync2_ssl*
openssl genrsa -out /etc/csync2_ssl_key.pem 1024
openssl req -new -key /etc/csync2_ssl_key.pem -out /etc/csync2_ssl_cert.csr
openssl x509 -req -days 600 -in /etc/csync2_ssl_cert.csr \
        -signkey /etc/csync2_ssl_key.pem -out /etc/csync2_ssl_cert.pem

Luego las llaves deben ser re-distribuidas entre cada nodo antes de correr csync2 nuevamente.

cyrus imapd

Para determinar cuales certificados están en uso, ver las directivas que sus nombres contengan "key_file" o "cert_file" en /etc/imapd.conf.

Generar nuevas llaves privadas y certificados como se describe en "Generic PEM Generation" arriba, y luego re-inicie el servicio:

invoke-rc.d cyrus21 restart

si usted está usando la versión 2.1 (si está usando otra versión, por favor examinar /etc/init.d para el nombre correcto del servicio)

dovecot

Generar un nuevo PEM como se describe en "Generic PEM Generation" arriba (asegurándose que está colocado en el sitios correcto, según su configuración particular de dovecot, y luego reinicie dovecot:  invoke-rc.d dovecot restart .

o:

rm /etc/ssl/certs/dovecot.pem
rm /etc/ssl/private/dovecot.pem
dpkg-reconfigure dovecot-common

dropbear

Ver [http://www.debian.org/security/key-rollover/#dropbear Official Key-Rollover page].

exim4

Si TLS está en uso, genere un nuevo PEM usando /usr/share/doc/exim4-base/examples/exim-gencert --force para obtener un certificado auto-firmado. Por omisión, el vencimiento es de tres años.

ftpd-ssl

Ver [http://www.debian.org/security/key-rollover/#ftpd-ssl Official Key-Rollover page].

Generic PEM Generation

Este es solo un recordatorio para aquellos que generan certificados codificados con PEM. Su sitio probablemente tiene otras políticas de cómo gerenciar las llaves, que usted debe seguir. Adicionalmente, es probable que tenga que firmar sus certificados de vuelta por un tercero (autoridad certificadora "3rd party Certificate Authority") en vez de usar certificados auto-firmados como se describe a continuación:

cd /etc/ssl/private
openssl genrsa 1024 > mysite.pem
cd /etc/ssl/certs
openssl req -new -key ../private/mysite.pem -x509 -days 9999 -out mysite.pem

(El último comando (openssl req.....) es todo en una sola línea, terminando con .pem)

gitosis

sudo -H -u gitosis gitosis-init < new_SSH_KEY.pub

revise todas las llaves bajo /var/cache/gitosis/repositories/gitosis-admin.git/gitosis-export/keydir/*.pub

(versiones más viejas en /var/cache/git)

OpenSSH (Servidor)

Ver también [http://www.debian.org/security/key-rollover/#openssh Official Key-Rollover page].

Paquetes actualizados para openssh que contienen lista negra de llaves débiles conocidas están disponibles actualmente. ver [http://www.debian.org/security/2008/dsa-1576 DSA 1576] para mayor información. Al instalar estos paquetes en servidores con llaves débiles, causará que el servidor ssh regenere sus llaves automáticamente. Las llaves débiles de clientes que sean usadas para conectarse serán rechadas en lo posible.

/!\ Note que tendrá que usar aptitude dist-upgrade (o apt-get dist-upgrade) para instalr estos paquetes en vez de solo upgrade porque esta actualización hará que el nuevo paquete openssh-blacklist se instale.

Comentario de Alejandro Imass: ¿No será mejor usar apt-pinning para este paquete en particular?

AYUDA DE UN EXPERTO Receta para apt-pinning del (los) paquetes necesarios para obtener openssh-blacklist.

También puede actualizar sus llaves de openssh-server manualmente.

rm /etc/ssh/ssh_host_*
dpkg-reconfigure openssh-server

/!\ Nota que en cualquier caso, sus usuarios verán la advertencia "IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!" la próxima vez que entren en su servidor ya que su llave ha cambiado. Deben editar el archivo $HOME/.ssh/known_hosts para remover la línea del problema antes de continuar; revisando que la huella de la llave sea la correcta, claro (la huella de su nueva llave puede ser determinada con ssh-keygen -l -f /etc/ssh/ssh_host_dsa_key). Usted puede remover la llave problemática de known_hosts corriendo "ssh-keygen -R hostname"

Adicionalmente debe notar que sus conexiones actuales de ssh no deben ser interrumpidas.

OpenSSH (Cliente)

Ver también [http://www.debian.org/security/key-rollover/#openssh Official Key-Rollover page].

Debe tener una lista de las llaves openssh que actualmente tiene y a donde han sido copiadas. Para cada llave que sea vulnerable:

cd ~/.ssh
ssh-keygen -t rsa -f filename
ssh-copy-id -i filename hostname 

Reemplazando rsa por dsa si prefiere llaves ds y reemplazando filename y hostname con los valores apropiados.

También recuerde remover las llaves comprometidas de su archivo .ssh/authorized_keys!

OpenSWAN

La generación cruda de RSA no es vulnerable, y no usa la librería openssl.

Esto quiere decir que todas las conexiones que usen authby=rsasigkey no son vulnerables.

Las llaves basadas en X.509 por administradores para ser usadas con IPsec pueden ser vulnerables si fueron creadas en un sistema Debian usando el comando openssl (según la documentación).

Ver [http://www.debian.org/security/key-rollover/#openswan Official Key-Rollover page].

StrongSWAN

Ver [http://www.debian.org/security/key-rollover/#openswan Official Key-Rollover page].

OpenVPN

Ver [http://www.debian.org/security/key-rollover/#openvpn Official Key-Rollover page].

Si está usando certificados x509, debe crear un CA completo si usted generó la llave CA con un OpenSSL roto. Incluso, si su llave CA no está comprometida, algunas de las llaves de los clientes OpenVPN pueden estarlo. En ese caso deberá revocar todos los certificados para esas llaves y añadir el CRL a la configuración de su OpenVPN. Ver [http://openvpn.net/index.php/documentation/howto.html#revoke OpenVPN HOWTO] para mayor información sobre la revocación.

postfix

Genere un nuevo PEM como está descrito en "Generic PEM Generation" arriba (asegurándose que es colocado en el sitio correcto según la configuración particular, y luego reinicie Postfix:  invoke-rc.d postfix restart .

puppet

Ver [http://www.debian.org/security/key-rollover/#puppet Official Key-Rollover page].

ssl-cert

Ver [http://www.debian.org/security/key-rollover/#ssl-cert Official Key-Rollover page].

telnetd-ssl

Ver [http://www.debian.org/security/key-rollover/#telnetd-ssl Official Key-Rollover page].

tinc

Ver [http://www.debian.org/security/key-rollover/#tinc Official Key-Rollover page].

Tor Onion Router / Hidden Service Keys

Ver [http://www.debian.org/security/key-rollover/#tor Official Key-Rollover page].

encfs

Análisis del impacto aún está siendo determinado. Detalles al momento incluyen: enfs usa RNG de libssl para crear una llave de encriptación interna con un poco de post-procesmiento aplicado. La revisión de esa llave contra una pre-calculada en una lista negra como se hace con dowkd.pl puede ser posible cuando esté listo.

Mientras tanto, los sistemas de archivo encriptados que pudieron haber sido creados usando la versión rota de libssl, deben ser considerados vulnerables contra ataques fuera de línea. Cualquier copia de datos localizados en un ambiente no-confiable podrá ser legible tarde o temprano. Si la fecha de creación es desconocida, se puede revisar la versión originadora en la salida del comando encfsctl contra el changelog del paquete encfs, y esto puede proveer algunas pistas, aunque no es absolutamente confiable porque no habían dependencias fuertes en algunas versiones particulares de openssl.

Para garantizar la seguridad, pruebe lo siguiente:

  • Cree otro sistema de archivo con enfs luego de actualizar a la última versión del openssl corregido.
  • Monte el sistema de archivos original y copie la data a la nueva ubicación.
  • Desmonte el sistema de archivos viejo y destruya toda la data con shred.

xrdp

Ver [http://www.debian.org/security/key-rollover/#xrdp Official Key-Rollover page].


LLEGUE HASTA AQUI


Kerberos (MIT and Heimdal)

If you were using MIT Kerberos, you would be fine so far as I can tell since MIT Kerberos has its own crypto layer and its own randomness functions. Heimdal uses OpenSSL as its crypto layer. Given that, it may well be possible to brute-force the session key of any captured GSSAPI-encrypted traffic and decrypt it retroactively.

If you're using Heimdal, you should also change all long-term random keys (such as any key in generated keytab files) that were generated using the vulnerable version of OpenSSL.

This can be done using cpw -r <principal> within kadmin. Take into account that this principals have been randomed-key assigned and should be regenerated as well.

kadmin/admin
kadmin/hprop
kadmin/changepw
changepw/kerberos
krbtgt/YOUR.REALM
host/SOMEHOST@YOUR.REALM
host/SOMEOTHERHOST@YOUR.REALM

Keys based on user passwords should be fine.

pwsafe

First issue: the random seed of the DBs is now the same. More exactly, the random, the salt and the iv. The random is fixed at creation of the DB. Apparently the seed & iv are renewed at every edition of the DB and depend only on a fresh random. Data encryption depend only on hash and seed/iv so even with different random, if the fresh random for seed is the same, the encrypted data is the same. A practical attack against a pwsafe DB is e.g. to construct a generic rainbow with the possible random seeds and your favorite character class. Once done it could attack any pwsafe DB generated with a broken OpenSSL or even edited with a broken OpenSSL (to be confirmed).

Second issue: all nice passwords proposed by pwsafe when creating a new entry are now broken! So are all the accounts you created around based on those passwords. No matter the DB/user/group/... you are using. Of course no matter how decently you seeded the RANDFILE ~/.rnd (cf man). To rekey your pwsafe, create a new one, import the old one then delete the old one:

$ pwsafe -f newdb --create
Enter passphrase for newdb: 
Reenter passphrase for newdb: 
$ pwsafe -f newdb --mergedb=/home/myself/.pwsafe.dat
Enter passphrase for newdb: 
Enter passphrase for /home/myself/.pwsafe.dat: 
Merged 247 entries; skipped 0; 0 duplicates.
$ wipe /home/myself/.pwsafe.dat
$ mv newdb /home/myself/.pwsafe.dat

And if you generated your account passwords with pwsafe, you should renew all those passwords...

(pwsafe information from http://wiki.yobi.be/wiki/Debian_OpenSSL#pwsafe )

slurm-llnl

Remove the vulnerable SLURM key files:

rm -f /etc/slurm-llnl/slurm.key /etc/slurm.cert

Generate new key pair with the commands:

openssl genrsa -out /etc/slurm-llnl/slurm.key 1024
openssl rsa -in /etc/slurm-llnl/slurm.key -pubout -out \
        /etc/slurm-llnl/slurm.cert

Copy the key files on the controller and the backup controller and the cert file on all the nodes of your cluster then restart SLURM with the command:

invoke-rc.d slurm-llnl restart

SSL Certificate Reissuance

If you paid good money to have a vulnerable key signed by a Certificate Authority (CA), chances are your CA can re-issue a certificate for free, provided all information in the CSR is identical to the original CSR. Create a new key with a non-vulnerable OpenSSL installation, re-create the CSR with the same information as your original (vulnerable) key's CSR, and submit it to your CA according to their reissuance policy

Testing keys using ssh-vulnkey

In the latest openssh-client packages for etch, ssh-vulnkey is included along with a blacklist of known weak keys. This tool appears to be similar to dowkd.pl (below) although it is restricted to checking ssh keys (not that dowkd.pl can do much more than that anyway).

Run ssh-vulnkey as a user to check your host and your own keys.

Run ssh-vulnkey -a as root to check all users keys (as well as the host key).

Sample output:

ssh-vulnkey -a
Not blacklisted: 2048 fa:2e:1d:a6:84:64:a1:80:c4:31:68:5a:b0:1a:cb:fe /etc/ssh/ssh_host_rsa_key.pub
Not blacklisted: 1024 f4:34:04:85:58:a0:6b:0a:a1:b9:2d:3b:e6:19:5a:76 /etc/ssh/ssh_host_dsa_key.pub
COMPROMISED: 2048 5c:10:8a:c0:55:8c:1f:d9:4b:05:f0:35:0a:0d:2f:5c /home/someuser/.ssh/authorized_keys
Not blacklisted: 2048 a7:b4:3e:41:18:cb:f7:68:5e:4f:ae:30:14:d2:17:fd /home/someuser/.ssh/authorized_keys

/!\ Note: about output is one line per key not linewrapped as shown here in the wiki

/!\ Note: openssh-blacklist-0.1.1 provided for Debian Etch does not include 4096bit or 1024bit RSA fingerprints. Instead, grab the openssh-blacklist-0.3 package from Debian Unstable and backport it, or grab ready-made debs for Etch from http://love.hole.fi/atte/openssh-blacklist/

Testing keys using dowkd.pl

The security team has prepared a utility for you to test your keys to see if they have a fingerprint that matches a list of known-weak finger prints. Download [http://security.debian.org/project/extra/dowkd/dowkd.pl.gz dowkd.pl.gz ] ([http://security.debian.org/project/extra/dowkd/dowkd.pl.gz.asc gpg signature]) /!\ Attention: This version is not the same than the original tool released by Florian Weimer. So the patches below will not apply!

Changes to the original version:

  • Added copyright note
  • Improved Note
  • Added verbose output
  • Better check for keytype/length matching
  • More robust
  • Integrated PEM support (Available with the file option)
  • Integrated support of the patches below (different implementation)
  • Added support other key lengts

As I (Klaus Ethgen) can see the tool do what it should (Version sha1:027adef3b86991661394b6ab6159d75dde3c3087 0.9). But please check yourself. Also if someone make update of the script please tell it on this page to not confuse users.

cd /tmp
wget http://security.debian.org/project/extra/dowkd/dowkd.pl.gz
wget http://security.debian.org/project/extra/dowkd/dowkd.pl.gz.asc
gpg --keyserver subkeys.pgp.net --recv-keys 02D524BE
gpg --verify dowkd.pl.gz.asc
gunzip dowkd.pl.gz

/!\ Note that dowkd.pl may produce false negatives. As of 2008-05-19, the current version of dowkd.pl prints warnings if a false negative is likely, except if the key in question has been generated on a big-endian architecture. If unsure, regenerate your key material.

Use dowkd.pl in the following ways:

SSH Server Host Key

Key is OK:

perl dowkd.pl host localhost
# localhost SSH-2.0-OpenSSH_4.3p2 Debian-9
# localhost SSH-2.0-OpenSSH_4.3p2 Debian-9

Key is weak:

perl dowkd.pl host localhost
# localhost SSH-2.0-OpenSSH_4.3p2 Debian-9
# localhost SSH-2.0-OpenSSH_4.3p2 Debian-9
localhost: weak key
localhost: weak key

A remote check based on the keys generated by HD Moore (http://metasploit.com/users/hdm/tools/debian-openssl/ ) is available at http://itsecurity.net. debian_ssh_scan_v3 now includes fingerprints of all weak DSA 1024, RSA 2048 and RSA 4096 bit keys.

root@box:~/debian_ssh_scan_v2# ./debian_ssh_scan_v2.py 10.128.15.110
65536 fingerprints loaded.
10.128.15.110:22 sshd fingerprint 9cf71acb1b0dff0dceef4f755f721e9d VULNERABLE (RSA 2048 bit key, pid 5252)

SSH User Key

To check one user (someuser):

perl dowkd.pl user someuser
/home/someuser/.ssh/authorized_keys:1: warning: unparsable line
/home/someuser/.ssh/authorized_keys:3: warning: unparsable line
/home/someuser/.ssh/authorized_keys:4: weak key
/home/someuser/.ssh/authorized_keys:5: weak key

Notes:

  • The complaints about lines 1 and 3 are because these lines are comment lines (starting with #) in the ~/.ssh/authorized_keys files (which are allowed, see man 8 sshd for the syntax).

  • Line 2 has a non-weak dsa key that should be replaced anyway according to the information provided above.
  • Lines 4 and 5 are rsa keys that are reported as being weak (note that both rsa and dsa keys are affected by this vulnerability)

To check all users:

perl dowkd.pl user

perl dowkd.pl user > /tmp/weak 2>/tmp/weak.err
./gethk.sh /tmp/weak
==== FILE: /root/.ssh/known_hosts:6:
10.0.0.4 ssh-rsa AAAAB3NzaC1[....]

==== FILE: /home/joe/.ssh/known_hosts:13:
10.0.0.1 ssh-rsa AAAAB3NzaC1[....]

PEM keys (SSL certificates)

The SSL server (and client) certificates, aka PEM keys, may be used in various tools (Apache + mod SSL, etc.).

The Ubuntu team has created a package which will verify if PEM files are vulnerable. I used it against PEM keys created on a known vulnerable system and the utility highlighted them as vulnerable. The package is called "openssl-blacklist". The package is available [http://security.ubuntu.com/ubuntu/pool/main/o/openssl-blacklist/openssl-blacklist_0.1-0ubuntu0.8.04.1_all.deb here]. It can be installed on etch using dpkg -i --force-all.

openssl-blacklist repackaged for Debian: attachment:openssl-blacklist_0.1-0%7Edebian-1_all.deb . Built for etch/stable, but should install cleanly on any later debian versions. I'm not uploading this to Debian proper at present, because I haven't checked whether anyone else is already doing that. For the (signed) sources, see http://xillion.org/openssl-blacklist/ . -- PaulCannon

There is a way to convert PEM files to SSH-style public keys, which the tool can parse. I've not verified this method completely, it comes from information found at: http://webjob.sourceforge.net/Files/Recipes/openssl-convert-ssl-key-to-ssh-keypair.txt

cp /etc/apache/ssl.key/your.keyfile.key ~/.ssh/id_ssl
ssh-keygen -y -f ~/.ssh/id_ssl  > ~/.ssh/id_ssl.pub
./dowkd.pl file ~/.ssh/id_ssl.pub

I have as yet not determined how accurate this method is, but it seems to work reliably. Someone more familiar with the workings of ssh-keygen can confirm the reliability of this method. Scripting this test should be easy enough.

  • If the code for generating the key in your PEM file used OpenSSL's random number generator even slightly differently than ssh-keygen from openssh, it's likely to have keys that are equally-weak but not contained in that blacklist. I wouldn't recommend drawing any conclusions from this method. -- ?MarshRay

  • Can you tell us how you tested this? We are unable to reproduce your results as none of the keys we generate with the known-weak version of openssl are flagged as being weak by dowkd.pl or dowkd.pl with RichiH's patch (below). Details of how those certificates were generated are below; are you doing the same? -- StuartPrescott

someone who actually understands this tool and its output, please insert details here!

  • I don't know what kind of information is being requested, but it seems fairly easy. On first invocation of the tool, it generates a DB file from the "blacklist" contained in the __DATA__ section of the script. If the DB exists, it is opened for reading. Once the DB exists, it uses ssh-keygen to retrieve the fingerprint of the public key presented to it by the executor of the script, and compares the fingerprint that it retrieves to the blacklist. If there is a match, then the script prints 'weak key'.

    • This is perhaps irrelevant now -- an earlier version of this tool didn't say "weak key" but just printed the key name. It also completely failed to parse correctly formed authorized_key files. Perhaps it has now been sufficiently refined as to now be understandable. This page has been a work in progress throughout the day and getting the bones of the content here so that it could then be added to by others was the priority. -- StuartPrescott

I created a patch to parse PEM files. fw told me to look at the Modulus of the RSA key, so I am doing that. Even though I tested more than 20 certificates generated on an affected machine, I did not find a single weak key. This could mean that

  • the list is incomplete
  • I am looking in the wrong place
  • the certificates are not, in fact, affected by this. Note that I did not generate them myself as I do not have any vulnerable hosts left

As I manually verified the results against, I do not think there is an error in my patch. It is worth noting that none of the certs showed any hits when I converted them into SSH format. Please test this and report back to me!

  • The Patch attachment:dowkd.pl.rh.patch.gz is not needed anymore!

To test this for yourself, do this

for i in $(seq 1 100)
do
    openssl genrsa 1024 > server$i.key 2>/dev/null
    echo -e "\n\n\n\n\n\n\n\n\n\n" | \
            openssl req -new -key server$i.key -days 365 -out server$i.req 2>/dev/null
    openssl x509 -req -days 365 -in server$i.req -signkey server$i.key -out server$i.crt 2>/dev/null
    chmod 600 server$i*
    ssh-keygen -y -f server$i.key > server$i.pub 2>/dev/null
    perl dowkd.pl file server$i.pub
    perl dowkd.pl pem server$i.crt
done

and please post your results.

  • When we were throwing test cases around on #debian (approx 2008-05-14 02:00 UTC for those who have logs), I threw together this script to run on an unpatched etch box. None of the keys were marked as weak by dowkd.pl when tested by either method even though the keys were generated by a known weak version of openssl. I can only conclude that these methods of testing this class of key for weakness must be incorrect. -- StuartPrescott

    • I think the existing blacklist works only for keys generated with ssh-keygen and a keylength oh 2048 bits. I tried to produce vulnerable keys on a vulenrable system with ssh-keygen and did not get any weak keys as per dowkd.pl for 1024 bits while 2048 bits worked every time. I also tried to generate 2048 bit keys with openssl genrsa and had no success either. I had a look at the generated keys and found that ssh-keygen uses 35 as public exponent while openssl uses 65535. So probably the blacklists don't fit again. Unfortunately this means we cannot use the script for checking keys generated with openssl until we get updated blacklists or a description how these were generated. -- Joachim Ring

The Patch for authorized_keys2 and known_hosts (attachment:dowkd.pl.ke.patch.gz) is not needed anymore. -- Klaus Ethgen

I have hacked a little shell script using the tables from openssl-blacklist from ubuntu which allows the user to check the ssl key of a webhost from remote by just calling "chksslkey hostname". You can find it here: attachment:chksslkey.tar.bz2 -- Michael Holzt

I threw together a little script that combines everyone elses and lets you test a cert, ssl rsa key, pem file, or remote https against the blacklist's. You can find it at [http://www.gokickrocks.us/wp-content/uploads/2008/05/audit-ssl.tar.gz]. Super easy to use, just take a peek at the README. Basic usage is just "chkssl testtype fileorurl". -- Florian Hines

Scope of the blacklists

The current official blacklists (in "openssh-blacklist") cover RSA-2048 and DSA-1024 keys as generated on 32-bit little-endian, 64-bit little-endian and 32-bit big-endian systems. That's sufficient to cover users who used the default key length, but not if some of your users decided they wanted a longer keylength. For non-default keys, see "openssh-blacklist-extra" which contains RSA-1024, RSA-4096, and (an empty) DSA-2048 for all three architectures.

  • I have made a blacklist for RSA-4096 keys as generated on 32/64-bit little-endian systems and posted it at http://www.red-bean.com/~maxb/ . The 64-bit keys I generated, the 32-bit ones I took from the metasploit site linked earlier on this page. The format is full fingerprints:

    • suitable for appending to dowkd.pl, if you also edit the body of the script so that it tries to check 4096 bit keys too
    • or, if you remove the first 12 characters from each line, suitable for use with ssh-vulnkey

    (There are also RSA-1024 and RSA-1023 versions there, potentially useful for the paranoid evaluation of older keys.) --?MaxBowsher

    I used MaxB's RSA-4096 fingerprint list for my unofficial openssh-blacklist-0.1.2, but it seems there is now openssh-blacklist-0.3 in Debian Unstable which includes these, and RSA-1024 which is also missing from the Etch package. I backported it for Debian Etch, grab it from http://love.hole.fi/atte/openssh-blacklist/ or backport yourself. --Atte Peltomäki

Technical Summary

(If you want to add more technical details that an end-user doesn't need to know or isn't likely to understand, please add them here rather than making the above summary impossible for the average user to understand.)

Causes

It is important to understand that this problem was caused by trying to remove valgrind warnings related to the use of uninitialised memory within the openssl libraries. This was done to try to make it easier to debug C applications that use the openssl libraries which is a good thing to do.

A discussion of why this change was made can be found at [http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=363516 #363516] and also on the [http://marc.info/?t=114651088900003&r=1&w=2 openssl-dev list]. Judging from the [http://www.links.org/?p=327#comment-176642 discussion there], the main culprit seems to be a misunderstanding about which is the right list to ask this question on, followed by misleading answers from the list.

A bit more detail

In an effort to clear up confusion about this bug, here's a bit more technical description. This was caused by an overzealous, well-intentioned elimination of code that was believed to have no impact on security. (Please do note from the above links that this was discussed with the !OpenSSL team and that no objections were raised at the time.)

So here's the problem: the Debian maintainer wanted very much to get rid of valgrind errors while using OpenSSL; certainly a noble cause, right? As you can see here, there are two identical lines,  MD_Update(&m, buf, j);  in SSL's md_rand.c file that were commented out way back in 2006: http://svn.debian.org/viewsvn/pkg-openssl/openssl/trunk/rand/md_rand.c?rev=141&view=diff&r1=141&r2=140&p1=openssl/trunk/rand/md_rand.c&p2=/openssl/trunk/rand/md_rand.c

The second of these is in  ssleay_rand_bytes  where  buf  is used as an output buffer. It had already been marked as a bad idea when -DPURIFY was in effect, because Purify (and valgrind, naturally) dislike this use of an output buffer as input. This use of  MD_Update  is dubious but shouldn't hurt as long as the mixing function of the PRNG is "sufficiently good". The removal of this call to MD_Update should not meaningfully alter the entropy available in the pool -- that is, OpenSSL does not depend upon uninitialized memory for its correct operation.

The first call, however, is in  ssleay_rand_add  where  buf  is used as an INPUT buffer, to add entropy to the pool. Failing to call  MD_Update  there means that the pool will never actually get the entropy intended for it.

Acknowledgements

This document was put together by the folks on [:] to help with user support. It would have been nice to have had the chance to prepare this (and the key rollover page) in the 5 days between the commit being made to pkg-openssl and the DSA being released. Particular credit to themill, dondelelcaro, stew, Maulklin, iobound for reading, writing and suggesting bits for this page. No thanks to the people who keep using the wiki's GUI editor and keep generating 15 to 20 KB diffs from when it randomly reformats the entire page when you only change one line.

See Also

http://www.debian.org/security/key-rollover/


CategorySystemSecurity