Samba Security Process
Below is the process the Samba Team follows to prepare a security release and co-ordinate the disclosure of a security vulnerability.
- Only supported Samba versions are eligible for a security release.
- Security updates, once public, are listed on Samba Security Releases
- Security issues that are assigned a CVE can be found in The Samba Bugzilla. This will also include some minor issues that do not warrant a full security release.
Reporting Security Defects in Samba
Please report all security issues or defects in Samba or concerning our infrastructure to firstname.lastname@example.org and never on IRC, public mailing lists or in Bugzilla!
For clarity, a Samba Team member will create the private Bugzilla issue mentioned below.
Some specific things not to report to Samba
- Samba is a public open source project, so we have a public gitweb instance at https://git.samba.org. This is intentional, please do not report this (again).
- HTTP Headers on https://www.samba.org and https://download.samba.org websites. Our main website is static, not dynamic nor a content management system.
- The private keys and network captures under https://www.samba.org/~metze/caps, in particular at https://www.samba.org/~metze/caps/krb5/pkinit/manage-ca/CA-w4edom-l4.base/Private/ are intentionally public samples.
A public security process for Samba
The following process is followed by the Samba Team Member working on the security issue.
We publish it as a service to the Free Software and broader software development community as a well-worked, practical process for responsible disclosure and to our aid our Samba community in knowing how we handle serious security issues in our code.
Security issues are usually reported via email@example.com. 1.) Someone should feel responsible and make sure that it's really a security defect. If yes, we need one person who is responsible for this specific issue beyond this point. This person coordinates the further actions and might delegate tasks, of course. 2.) Create a bug report with limited access to "Samba core developers" only! This is done by selecting 'Show advanced fields' and at the very bottom: 'Only users in all of the selected groups can view this bug: [x] Samba Core Developers 2a.) Change the summary so that it starts with "[EMBARGOED][SECURITY]" For example: "[EMBARGOED][SECURITY] dsdb: time wrap at end of unix time 2b.) Add all information including reproducer etc. to the bug report. 3.) Write an initial advisory and attach it to the bug report. A template is available here: team-info/doc/releases/template_security_advisory.txt 3a.) Confirm with the initial reporter that they are willing to be publicly thanked and any affiliation they wish to have noted. 4.) Do a CVSSv3.1 calculation () and add it to the bug report and the advisory. 4a.) Stop and ask for advise on firstname.lastname@example.org if the CVSSv3.1 score is less than 5.0. This is a heavy-weight process with costs to many parties. 4b.) Even for a CVSSv3.1 of more than 5.0 we do not do a security release where the impact is: * Only a Denial of Service (not a use after free) and the automated internal process restart will allow other clients to reconnect eventually. For clarity, the shared LDAP or KDC process in the AD DC will restart, so a simple NULL de-reference crash there would not trigger a release. However a similar issue in the main smbd listener preventing new connections being established may require a release. This is similar to, but an extension of, our existing rule that crashing the smbd belonging to the connecting user is not a DoS. * Mitigated by the selection of strong passwords. We will not do a security release simply because weak passwords are permitted to be selected (eg our password policy tools fail to exclude all weak passwords) or a weak password can be brute forced online (eg avoiding a bad password lockout). These issues are real, important and should be backported to maintained releases, but do not justify the costs of coordinated disclosure or a seperate security release. However, we do: - ask for a CVE (step 5.) - place the CVE on the bug (step 5b.) - leave or make the bug public (step 14. and 14a.) - mark the commits with the CVE (step 6a.) 4c.) In general we do not take security release steps at all where the issue is: * Samba's historical acceptence of now-weak cryptography Unless of course a new novel attack is found, rather than just the slow march of time. * Reliant on a timing attack For example newer Samba versions use a constant-time memcmp() from GnuTLS. The failure of this to be constant-time or the lack of use of constant-time methods in a particular place will just be fixed normally. * User enumeration / username discovery It is assumed that in our deployed environments usernames are available to an attacker. In the AD DC Kerberos will readily confirm that a user does or does not exist. * Relient on offline brute force of a weak password The NTLM challenge response and Kerberos traffic (without FAST, which is rare) is well known to expose a user's password to a brute force attack. However do ask for advise on email@example.com if you feel concerned that any particular issue may be an exception. 5.) Ask for a CVE (usually Red Hat Product Security <firstname.lastname@example.org> does help out on this one). To: Red Hat Product Security <email@example.com> Subject: Another Samba CVE (bug XXXX) Red Hat Product Security, Can I please get a CVE for what will be Samba Bugzilla: https://bugzilla.samba.org/show_bug.cgi?id=14706 The Samba team has evaluated this issue and determined that it will require a CVE per our process. https://wiki.samba.org/index.php/Samba_Security_Process Details are confidential for now, but will be clearly marked with that bug (so you can connect the threads once vendors are notified or the issue is made public). Thanks! If the bug is already public, remove "are confidential for now, but " and feel free to describe the issue in cleartext. DO NOT attach the advisory from step 3. This avoids two issues: - If Red Hat gets the advisory, they need to get GDPR permission for the reporter name and we don't want to block on the back and forth for that (see 3a). - It keeps all vendors on the same basis. See  for GPG key etc if the circumstances require it (if for example you do feel the need to disclose details or seek detailed advice). 5b.) If for any reason Red Hat is unable to assist with obtaining a CVE number in time, the backup process is to fill in this form https://cveform.mitre.org/ (explain the situation in the submission) 5c.) After receiving the CVE number, please add it as an alias (this is a seperate bugzilla field) on the bug report and to the summary (title), eg: CVE-2038-12345 [EMBARGOED][SECURITY]... 6.) Write patches and tests and add them to the bug report. Mark them WIP in the description until they are 'final'. (Even 'final' patches may change after being subject to review of course). 6a.) ALL commits in the patch should have a CVE prefix and a BUG tag eg: CVE-2038-12345 dsdb: time wrap at end of unix time At time_t rollover all AD security is lost due to integer wrap on 32-bit systems BUG: https://bugzilla.samba.org/show_bug.cgi?id=999999 Signed-off-by: Time Lord <firstname.lastname@example.org> 6b.) Ask for early review of your WIP and final master patches ASAP 6c.) Prepare backports for all affected and supported versions (1 file per version, even if identical). Files should be named $CVE-$DESCRIPTION-$MAJOR-$VERSION.patch E.g.: CVE-2018-14629-timewrap-4.9-01.patch 6d.) Run *private* autobuild (see doc/autobuild.txt) or *private* Gitlab CI for each CVE and each maintained branch. (This allows the release manager to defer some patches if problems appear later in the process). 6e.) Mark the patch that has passed with the ci-passed flag in the bugzilla attachment details. 6f.) Once each CVE patch and branch has passed, ask for review ASAP. 6g.) Get one explicit review flag in Bugzilla (yours, as a team member, is implicit and CI passed is now a distinct flag). 7.) Once all patches and the advisory are available and reviewed, ask the release manager for a release date. 7a.) Between now and the release, the release manager or their delegate will run a *private* autobuild of the exact combination of patches the be released. 7b.) If multiple issues are being released in a batch, create a tracking bug that is blocked by the CVEs to be addressed in this bundle. 8.) Finish the advisory and attach it to the bug report as advisory-$CVE.txt. Ask for review. (This must be after getting the release date so the correct version numbers can be included). 9.) ~10 days before the release date, confirm every patch and the CVE text still has the correct reviews (due to additional feedback for example). 9a.) add samba-vendor to the CC list in the bug report, 9b.) open the bug report by checking "Core developers, and Vendors shipping Samba as part of their products" and removing "Samba Core Developers". 9c.) Add the planned release date to the bug or the tracking bug if that has been created. This will be the first useful e-mail seen by our vendors. 10.) 7 days before the release date, send an e-mail to email@example.com, firstname.lastname@example.org and email@example.com indicating there will be a security release and the broad component it impacts. This is to allow large installations time to prepare for security patching. For example: To: firstname.lastname@example.org Cc: Upstream Samba Technical Mailing list <email@example.com>, firstname.lastname@example.org Subject: Heads-up: Security Releases ahead! Hi, this is a heads-up that there will be Samba security updates on Tuesday, XXXXX YYth. Please make sure that your Samba servers will be updated soon after the release! Impacted components: - AD DC (CVSS 7.5, High) - client (CVSS 5.9, Medium) - file server / classic DC (CVSS 6.8 Medium) 10a.) Note that this represents the final GO/NO-GO point. In order to facilitate creation of tarballs etc, after this date the patches and CVE text *must not change* or else the release will need to be publicly rescheduled, patches dropped or other appropriate action taken at the absolute discretion of the release manager. 11.) The release manager or their delegate will prepare the tarballs in the *stable* branches: - git fetch - git rebase - git merge -ff-only the VERSION bump commit from the corresponding test branch - apply the security patchset - WHATSNEW.txt: add the release notes - VERSION: disable GIT_SNAPSHOT - add an empty announce.samba-$VERSION.quotation.txt file - GNUPGHOME=$PATH_TO_THE_RELEASE_KEY script/release.sh samba-stable create DO NOT PUBLISH ANYTHING BEFORE THE END OF EMBARGO! On the release day: Upload the files and publish the announcements as described in steps 3.) and 4.) in team-info/doc/releases/howto_releases.txt 12.) Additional steps for the release manager: - upload the signed security patch(es) to the ftp server: email@example.com:/home/ftp/pub/samba/patches/security/ - push the advisory to the samba-web git repository: samba-web/security/ - update samba-web/history/security.html Merge the tags to the test branches: - git fetch - git rebase - git merge $TAG - VERSION: bump version - push without autobuild: LC_SAMBA_AUTOBUILD_PUSH=1 git push-v4-X-test-skip-autobuild 13.) After shipping the releases, the responsible person must make sure that the patches find their way into the master branch and remove the [EMBARGOED] tag from the bug report. 14.) Mark as 'private' any sensitive comments or attachments 14a.) Then un-select the "Core developers, and Vendors shipping Samba as part of their products" restriction. 15.) Address any minor improvements that were suggested after the patches were frozen and incorporate those into commits in master. 16.) Close out bug report when patches have been pushed to *all* relevant branches. 17.) Now that any regressions etc will have been broadly noticed, remove samba-vendor from the CC list of the now public bug, ask that they subscribe individually if still interested.  https://access.redhat.com/security/team/contact/  https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator
Template security advisory
The template security advisory is here: File:Template security advisory.txt
There is a Video of a presentation by Jeremy Allison about this security process in practice.