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Diffstat (limited to 'fetchmail-SA-2009-01.txt')
| -rw-r--r-- | fetchmail-SA-2009-01.txt | 25 |
1 files changed, 19 insertions, 6 deletions
diff --git a/fetchmail-SA-2009-01.txt b/fetchmail-SA-2009-01.txt index 93622c99..f1293e53 100644 --- a/fetchmail-SA-2009-01.txt +++ b/fetchmail-SA-2009-01.txt @@ -50,13 +50,26 @@ run time. Moxie Marlinspike demonstrated in July 2009 that some CAs would sign certificates that contain embedded NUL characters in the Common Name or -subjectAltName fields of ITU-T X.509 certificates. Applications what -would treat such strings in X.509 as NUL-terminated C strings (rather -than strings that contain an explicit length field) would only -check the part up to and excluding the NUL character, so that +subjectAltName fields of ITU-T X.509 certificates. + +Applications that would treat such X.509 strings as NUL-terminated C +strings (rather than strings that contain an explicit length field) +would only check the part up to and excluding the NUL character, so that certificate names such as www.good.example\0www.bad.example.com would be -mistaken as a certificate name for www.good.example. The CA however -would usually sign example.com and not care about the subdomain. +mistaken as a certificate name for www.good.example. fetchmail also had +this design and implementation flaw. + +Note that fetchmail should always be forced to use strict certificate +validation through either of these option combinations: + + --sslcertck --ssl --sslproto ssl3 (for service on SSL-wrapped ports) +or + --sslcertck --sslproto tls1 (for STARTTLS-based services) + +(These are for the command line, in the rcfile, you will need to omit +the respective leading --). + +The default is relaxed checking for compatibility with historic versions. 3. Solution |