Security Sheriff

Important Links

Chrome Open Security Bugs dashboard, go/chrome-security-bugs.

Vulnerability Severity Guidelines.

Security Labels.

Sheriff Handoff Log (Googlers only).

You might also like the HOWTO: Be A Security Sheriff deck.

What Is A Security Sheriff?

A security sheriff is a member of a rotation that occurs in 1-week time slots, starting on Tuesdays and ending the following Monday. Here is the rotation schedule.

Sheriffs ensure that all incoming security issues are triaged quickly and correctly. We aim to have get every bug triaged and assigned within 48 hours (preferably 24). This includes weekends, so it's good for sheriffs to check in once on a weekend and see if there are any emergencies.

Sheriffing is not an on-call rotation, however. Sheriffs don‘t have to work nights or to do more than a few minutes’ work on weekends.

I'm The Security Sheriff. What Do I Do?

Each week has a primary and secondary sheriff, and during their rotation both have various important and overlapping responsibilities:

Primary Sheriff

Secondary Sheriff

  • Ensure that all incoming queries to the and lists get a reply (by someone; not necessarily the sheriffs themselves).
  • Ensure accurate label management on bugs, for example applying the correct Merge-? and Restrict-View-? labels when a bug transitions to Fixed.
  • Change bugs status to Fixed for those that the developer forgets to close. Make sure to read bug comments where developer might point out that it needs more CLs, et c. Wait 24 hours before closing ClusterFuzz bugs, to give ClusterFuzz a chance to close it automatically.
  • Look at open security bug reports and check that progress is occurring.
  • Generally keep an eye on all bug traffic in case anything needs action or replying to.
  • Stay sharp, keep in shape (finger exercises are standard for the secondary sheriff), and remember you may be called upon during emergencies.

Life Of A Security Bug

Do as much as you can for the week to triage, shepherd, and wrap up open security bugs. What follows are the details of what that entails, but it practically means turning all the red cells in the dashboard to green. If you're ever stuck or in doubt, ask for help on #chrome-security!

alt text


Diagnose The Issue

alt text

  • If the report is invalid, remove the Restrict-View-SecurityTeam label and mark it WontFix.
  • If the report is a duplicate, mark it Duplicate. If the issue this is a duplicate of is public, remove the Restrict-View-SecurityTeam label.
  • If the report is primarily a privacy issue, send it to the privacy team:
    • Add the Privacy component so that it enters their triage queue
    • CC any security team members, including yourself, who may be interested in the privacy issue
      • Change the Restrict-View-SecurityTeam label to Restrict-View-ChromePrivacy
      • Note that security team members don't automatically have privacy bug access, so this will probably make the issue inaccessible to you.
  • If the report is asking about why something is or is not on the Safe Browsing list:
    • Assign it to zbutler@, who will triage it for the Safe Browsing team
      • Remove the Restrict-View-SecurityTeam label and add the Restrict-View-Google label
    • Change Type-Bug-Security label to Type-Bug
    • Add the Security component
  • If the report is a potentially valid bug but is not a security vulnerability:
    • remove the Restrict-View-SecurityTeam label. If necessary, add one of the other Restrict-View-? labels:
      • Restrict-View-Google if this is a crash report
      • Restrict-View-EditIssue if the bug can be abused (e.g. denial of service)
      • Change Type-Bug-Security label to Type-Bug (or whatever Type-? is appropriate)
    • Add appropriate component or CCs to ensure it does get triaged
    • Add the Security component or the Team-Security-UX label if the security team should still track the issue (e.g. security features).
  • If the report doesn't have enough information, ask the reporter for more information, add the Needs-Feedback label and wait for 24 hours for a response.
  • If the report smells like a vulnerability, keep going.

Verify And Label The Bug

Step 1. Reproduce legitimate-sounding issues.

If you can't reproduce the issue, ask for help on IRC (#chrome-security), or find an area owner to help.

Tips for reproducing bugs:

Step 2. Assess the severity.

See the severity guidelines. If it's a critical vulnerability, act quick! We aim to get users patched in < 30 days. Remember that if something requires an unusual configuration or complicated user interaction, the severity rating should be lowered.

Bug chains are typically composed of several individual security bugs and should be split into a new bug for each potential fix required, so this allows each team to work on fixing their part of the chain. In cases like this, leave the main bug as the severity/priority of the full chain, and mark child bugs as being blockers of the parent bug each with their own separate severity. Each child bug can have its own priority. Examples of this in action are issue 352369 and issue 453937.

Step 3. Label, label, label.

Much of Chrome's development and release process depends on bugs having the right labels and components. Labels and components are vitally important for our metrics, the visiblity of bugs, and tracking our progress over time.

Labels to double-check (that should already be there if the bug was filed using the Security template):

  • Restrict-View-SecurityTeam
  • Type-Bug-Security
  • If the reporter wants to remain anonymous or if the bug description or comments contain PII, add Restrict-View-SecurityEmbargo.

Generally, see the Security Labels document.

Ensure the comment adequately explains any status changes. Severity, milestone, and priority assignment generally require explanatory text.

  • Report suspected malicious URLs to SafeBrowsing.
  • Report suspected malicious file attachments to SafeBrowsing and VirusTotal.
  • Make sure the report is properly forwarded when the vulnerability is in an upstream project, the OS, or some other dependency.
  • For vulnerabilities in services Chrome uses (e.g. Omaha, Chrome Web Store, SafeBrowsing), make sure the affected team is informed and has access to the necessary bugs.

Find An Owner To Fix The Bug

That owner can be you! Otherwise, this is one of the more grey areas of sheriffing. With experience, you'll figure out good goto people for certain areas. Until then, here are some tips.

Determine the correct component before continuing. It‘s not enough on its own, but it’s a good starting point. Many components will automatically apply some CCs who may be able to help you out. If it's a crash bug, see if ClusterFuzz is able to provide one (will appear in the same card as the culprit CL). You can also use git hyper-blame and check OWNERS files to see who might own the relevant code.

For crashes, check to see if ClusterFuzz provides a culprit CL. Before you assign a bug based on this, do a quick sanity check to ensure the CL could have caused the bug. If the result seems wrong, apply the Test-Predator-Wrong label to the bug and keep going.

If you‘re able to narrow this to a specific regression range, usually from ClusterFuzz for crash bugs, do a quick pass over the git log to see if any CLs stand out. If you aren’t sure, don't be afraid to add CCs to the bug and ask!

At this point, you‘ll probably need to dive in and attempt to root cause the bug, which is another complicated grey area that you’ll figure out with experience. Try not to spend too much time for this on any given bug, as some cases will simply be too difficult without a deep understanding of certain portions of the codebase.

  • If you can narrow the bug to a specific file or block of code, or if something stands out as suspicious, try to assign an owner based on git hyper-blame or add some CCs based on OWNERS files
  • If not, consider searching in the issue tracker for people that fixed similar bugs or bugs in similar areas of the code base, such as issues with the same components, recently. For example, let's say you were trying to figure out a good person to assign a Content>Fonts issue. Look for “status=fixed, verified” and query by when the issues were closed after (i.e. w/ in the last 30 days == closed>today-30).

A few components have their own triage processes or points of contact who can help.

  • V8 bugs? Look for V8 rolls within the regression range, then look within the CLs of those rolls to find possible culprits. If you are unable to find the culprit CL, assign to the V8 ClusterFuzz Sheriff for triage. Note that V8 CHECK failure crashes can have security implications, so don't triage it yourself and instead assign it to V8 ClusterFuzz Sheriff. He or she can make an informed decision on whether it is a security vulnerability or not and whether it is safe to strip the security tags (Type=Bug-Security, Restrict-View-SecurityTeam).
  • Skia bugs? If you made it this far and still aren‘t sure, assign them to Be careful while triaging these! The place where we’re crashing isn't necessarily the place where the bug was introduced, so blame may be misleading.
  • URL spoofing issues, especially related to RTL or IDNs? See go/url-spoofs for a guide to triaging these.

Still stuck? Ask #chrome-security or someone from go/chrome-security-secondary-sheriffs for help! That‘s why we’re here. Don't be afraid to do this!

Make sure that the person you assign to handle a bug is not OOO. And, generally, explicitly CC more than 1 person on the bug, if possible, and preferably people from more than 1 geographic region. (See the OWNERS file(s) that affect(s) the relevant area of code.)

Sometimes, finding an owner isn't enough to ensure that a bug will get fixed. Check the stale bug list on the security dashboard and try resolve some of the problems that might be blocking these issues. If you get in touch with a bug owner off of the issue tracker, be sure to have them update the bug so that future sheriffs are aware of the status.

Q: Why isn’t setting the component alone good enough?

A: CCs are critical because just assigning to a component is ineffective because the component’s team cannot see the issues unless they have the Security View permissions.

Using The Permission API Kill Switch

If you find a vulnerability in a Permission API and need to use the Global Permissions Kill Switch, then follow the instructions

Wrap Up The Fixed Issue

  1. For any Security_Severity-{Critical, High, Medium} bugs that Security_Impact-{Beta, Stable}, add Merge-Requested so that the fix gets merged into the next release. Exercise discretion according to security severity and risk associated with the bug fix; you can ask the patch author whether any risky code paths are affected. The actual merging and drafting of release notes is taken care of by the security release management role.
  2. Chrome‘s Vulnerability Rewards Program TPM adds the reward-topanel label by mass modification, but do label any bugs reported by a email that should be rewarded (e.g. "I’m filing this on behalf of" or the like).

End Of Rotation

Update the Sheriff Handoff Log.