CVE-2017-7692

SquirrelMail 1.4.22 (and other versions before 20170427_0200-SVN) allows
post-authentication remote code execution via a sendmail.cf file that is
mishandled in a popen call. It’s possible to exploit this vulnerability to
execute arbitrary shell commands on the remote server. The problem is in
the Deliver_SendMail.class.php with the initStream function that uses
escapeshellcmd() to sanitize the sendmail command before executing it. The
use of escapeshellcmd() is not correct in this case since it doesn’t escape
whitespaces, allowing the injection of arbitrary command parameters. The
problem is in -f$envelopefrom within the sendmail command line. Hence, if
the target server uses sendmail and SquirrelMail is configured to use it as
a command-line program, it’s possible to trick sendmail into using an
attacker-provided configuration file that triggers the execution of an
arbitrary command. For exploitation, the attacker must upload a sendmail.cf
file as an email attachment, and inject the sendmail.cf filename with the
-C option within the “Options > Personal Informations > Email Address”
setting.

Notes