Date: Fri, 6 Jan 2017 22:51:10 +0100 From: Lizzie Dixon <_@...zie.io> To: oss-security@...ts.openwall.com Subject: Re: Re: Firejail local root exploit Hello oss-security, I was inspired by this thread so I took a look as well. I noticed that firejail allows ptrace with --allow-debuggers, which allows a sandboxed program to escape the seccomp profile by rewriting permitted system calls into unpermitted ones pre-Linux-4.8. This is documented in the seccomp manpage: http://man7.org/linux/man-pages/man2/seccomp.2.html > Before kernel 4.8, the seccomp check will not be run again > after the tracer is notified. (This means that, on older > kernels, seccomp-based sandboxes must not allow use of > ptrace(2)—even of other sandboxed processes—without extreme > care; ptracers can use this mechanism to escape from the > seccomp sandbox.) (I wrote a little program demonstrating this behavior last year at https://blog.lizzie.io/linux-containers-in-500-loc.html#fn.51 ). I emailed the author and they commited a fix (within 45 minutes!): https://github.com/netblue30/firejail/commit/6b8dba29d73257311564ee7f27b9b14758cc693e#diff-18143ef0a33f3f378f310a976725f141R80 Should this have a CVE id as well? Best, Lizzie. On 01/06, cve-assign@...re.org wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA256 > > > 1. --tmpfs > > Use CVE-2016-10117. > > > > 2. Nuke /etc/resolv.conf > > Use CVE-2016-10118. > > > > /tmp was mounted tmpfs 0777 prior to: > > > > commit aa28ac9e09557b833f194f594e2940919d940d1f > > Use CVE-2016-10119. > > > > /dev, /dev/shm, /var/tmp, /var/lock were mounted 0777 prior to: > > > > commit cd0ecfc7a7b30abde20db6dea505cd8c58e7c046 > > Use CVE-2016-10120. > > > > There are other weak perms fixed around here eg /dev/shm/firejail was > > 0777 prior to: > > > > commit 1cab02f5ae3c90c01fae4d1c16381820b757a3a6 > > Use CVE-2016-10121. > > > > 4. Environment not cleaned before root exec() > > Use CVE-2016-10122. > > > > don't allow --chroot as user without seccomp support > > Use CVE-2016-10123. > > - -- > CVE Assignment Team > M/S M300, 202 Burlington Road, Bedford, MA 01730 USA > [ A PGP key is available for encrypted communications at > http://cve.mitre.org/cve/request_id.html ] > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1 > > iQIcBAEBCAAGBQJYb1OiAAoJEHb/MwWLVhi2N9kP/0AHycN7Au+PTq/bHoxXVi4l > 74YrEI8PcE1UHIkL2m1kOLbZGTWWc8E0uMEJFTfKrVoIPAINN3iYtU9dYukSACxu > 4gyQK8xWuzpbqBeF/PIBaZsp9THvTy7sfz2dKYDh/n5i0AFRv34/cs8BUIcl9BDE > 4D/1FgdwLqarh0SJvclJRBmi4zmftqub3xbt1dJItSfc/5u5SxWMHqHbmW5vESIf > y3LU27S7E2qnSARfHxk1HfdqViDQO/76yYLQqlfGRc23wyj7ydFWQpRC28x0jjOL > SCiC91a2gG7nGyV1l/uFIF8QAQMACNl3uJT/5Hgp8ugUOVAko81u/o0liNJMthRK > NGWhENcFRuHqlqqxvOME/DfErfa7gn2cgFi+udl2BMfllCJb2ICH+Ddg9joaFLfu > 33iPga5J0MB5YSPQYoCSERjz2Q/i65P9kzgeTjGRLOhHsfY4p6yxUr/YmqTJ9E+W > DXiTCbpxNJXEsopKwHODBD4ausPQ83A8LGPine7eGaJKoW3q8UdphDqOqitCRFEL > d/XkVjtt44N0wgjB/ABDezrRAYbRPSudcCDPYh7WVl6V/6D0YRuaqYJ/Q8LlT+Nl > /17KzyEunx/+0lBjvdtyGz2UQN8F7+9XKl/S0ZRBJS9i+Hrb4ShctP53h2aNbTQT > nC4OrYY4JBuW90DY4Ef2 > =DJ5s > -----END PGP SIGNATURE-----
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