Remove sensitive files and their commits from Git history

Changing your passwords is a good idea, but for the process of removing password's from your repo's history, I recommend the BFG Repo-Cleaner, a faster, simpler alternative to git-filter-branch explicitly designed for removing private data from Git repos.

Create a private.txt file listing the passwords, etc, that you want to remove (one entry per line) and then run this command:

$ java -jar bfg.jar  --replace-text private.txt  my-repo.git

All files under a threshold size (1MB by default) in your repo's history will be scanned, and any matching string (that isn't in your latest commit) will be replaced with the string "***REMOVED***". You can then use git gc to clean away the dead data:

$ git gc --prune=now --aggressive

The BFG is typically 10-50x faster than running git-filter-branch and the options are simplified and tailored around these two common use-cases:

• Removing Crazy Big Files
• Removing Passwords, Credentials & other Private data

Full disclosure: I'm the author of the BFG Repo-Cleaner.

If you pushed to GitHub, force pushing is not enough, delete the repository or contact support

Even if you force push one second afterwards, it is not enough as explained below.

The only valid courses of action are:

• is what leaked a changeable credential like a password?

  • yes: modify your passwords immediately, and consider using more OAuth and API keys!

  • no (naked pics):

    • do you care if all issues in the repository get nuked?

      • no: delete the repository

      • yes:

        • contact support
        • if the leak is very critical to you, to the point that you are willing to get some repository downtime to make it less likely to leak, make it private while you wait for GitHub support to reply to you

Force pushing a second later is not enough because:

• GitHub keeps dangling commits for a long time.

  GitHub staff does have the power to delete such dangling commits if you contact them however.

  I experienced this first hand when I uploaded all GitHub commit emails to a repo they asked me to take it down, so I did, and they did a gc. Pull requests that contain the data have to be deleted however: that repo data remained accessible up to one year after initial takedown due to this.

  Dangling commits can be seen either through:

  • the commit web UI: https://github.com/cirosantilli/test-dangling/commit/53df36c09f092bbb59f2faa34eba15cd89ef8e83 (Wayback machine)
  • the API: https://api.github.com/repos/cirosantilli/test-dangling/commits/53df36c09f092bbb59f2faa34eba15cd89ef8e83 (Wayback machine)

  One convenient way to get the source at that commit then is to use the download zip method, which can accept any reference, e.g.: https://github.com/cirosantilli/myrepo/archive/SHA.zip

• It is possible to fetch the missing SHAs either by:

  • listing API events with type": "PushEvent". E.g. mine: https://api.github.com/users/cirosantilli/events/public (Wayback machine)
  • more conveniently sometimes, by looking at the SHAs of pull requests that attempted to remove the content

• There are scrappers like http://ghtorrent.org/ and https://www.githubarchive.org/ that regularly pool GitHub data and store it elsewhere.

  I could not find if they scrape the actual commit diff, and that is unlikely because there would be too much data, but it is technically possible, and the NSA and friends likely have filters to archive only stuff linked to people or commits of interest.

If you delete the repository instead of just force pushing however, commits do disappear even from the API immediately and give 404, e.g. https://api.github.com/repos/cirosantilli/test-dangling-delete/commits/8c08448b5fbf0f891696819f3b2b2d653f7a3824 This works even if you recreate another repository with the same name.

To test this out, I have created a repo: https://github.com/cirosantilli/test-dangling and did:

git init
git remote add origin [email protected]:cirosantilli/test-dangling.git

touch a
git add .
git commit -m 0
git push

touch b
git add .
git commit -m 1
git push

touch c
git rm b
git add .
git commit --amend --no-edit
git push -f

See also: How to remove a dangling commit from GitHub?

git filter-repo is now officially recommended over git filter-branch

This is mentioned in the manpage of git filter-branch in Git 2.5 itself.

With git filter repo, you could either remove certain files with: Remove folder and its contents from git/GitHub's history

pip install git-filter-repo
git filter-repo --path path/to/remove1 --path path/to/remove2 --invert-paths

This automatically removes empty commits.

Or you can replace certain strings with: How to replace a string in a whole Git history?

git filter-repo --replace-text <(echo 'my_password==>xxxxxxxx')

For all practical purposes, the first thing you should be worried about is CHANGING YOUR PASSWORDS! It's not clear from your question whether your git repository is entirely local or whether you have a remote repository elsewhere yet; if it is remote and not secured from others you have a problem. If anyone has cloned that repository before you fix this, they'll have a copy of your passwords on their local machine, and there's no way you can force them to update to your "fixed" version with it gone from history. The only safe thing you can do is change your password to something else everywhere you've used it.

---

With that out of the way, here's how to fix it. GitHub answered exactly that question as an FAQ:

Note for Windows users: use double quotes (") instead of singles in this command

git filter-branch --index-filter \
'git update-index --remove PATH-TO-YOUR-FILE-WITH-SENSITIVE-DATA' <introduction-revision-sha1>..HEAD
git push --force --verbose --dry-run
git push --force

Update 2019:

This is the current code from the FAQ:

  git filter-branch --force --index-filter \
  "git rm --cached --ignore-unmatch PATH-TO-YOUR-FILE-WITH-SENSITIVE-DATA" \
  --prune-empty --tag-name-filter cat -- --all
  git push --force --verbose --dry-run
  git push --force

Keep in mind that once you've pushed this code to a remote repository like GitHub and others have cloned that remote repository, you're now in a situation where you're rewriting history. When others try pull down your latest changes after this, they'll get a message indicating that the changes can't be applied because it's not a fast-forward.

To fix this, they'll have to either delete their existing repository and re-clone it, or follow the instructions under "RECOVERING FROM UPSTREAM REBASE" in the git-rebase manpage.

Tip: Execute git rebase --interactive

---

In the future, if you accidentally commit some changes with sensitive information but you notice before pushing to a remote repository, there are some easier fixes. If you last commit is the one to add the sensitive information, you can simply remove the sensitive information, then run:

git commit -a --amend

That will amend the previous commit with any new changes you've made, including entire file removals done with a git rm. If the changes are further back in history but still not pushed to a remote repository, you can do an interactive rebase:

git rebase -i origin/master

That opens an editor with the commits you've made since your last common ancestor with the remote repository. Change "pick" to "edit" on any lines representing a commit with sensitive information, and save and quit. Git will walk through the changes, and leave you at a spot where you can:

$EDITOR file-to-fix
git commit -a --amend
git rebase --continue

For each change with sensitive information. Eventually, you'll end up back on your branch, and you can safely push the new changes.

I recommend this script by David Underhill, worked like a charm for me.

It adds these commands in addition natacado's filter-branch to clean up the mess it leaves behind:

rm -rf .git/refs/original/
git reflog expire --all
git gc --aggressive --prune

Full script (all credit to David Underhill)

#!/bin/bash
set -o errexit

# Author: David Underhill
# Script to permanently delete files/folders from your git repository.  To use 
# it, cd to your repository's root and then run the script with a list of paths
# you want to delete, e.g., git-delete-history path1 path2

if [ $# -eq 0 ]; then
    exit 0
fi

# make sure we're at the root of git repo
if [ ! -d .git ]; then
    echo "Error: must run this script from the root of a git repository"
    exit 1
fi

# remove all paths passed as arguments from the history of the repo
files=$@
git filter-branch --index-filter \
"git rm -rf --cached --ignore-unmatch $files" HEAD

# remove the temporary history git-filter-branch
# otherwise leaves behind for a long time
rm -rf .git/refs/original/ && \
git reflog expire --all && \
git gc --aggressive --prune

The last two commands may work better if changed to the following:

git reflog expire --expire=now --all && \
git gc --aggressive --prune=now