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Thursday, October 14, 2021

Resetting a Windows guest’s Administrator password with guestfish

DISCLAIMER: This is not my post is only a copy; in case the original gets deleted or whatever, posting on my personal blog gets more accessible for me to find it. You can find the original one in this link at the end of the post. 

I recently found myself with a Windows guest for which I didn’t have the Administrator password or any way of getting it. Nevertheless, I needed to make configuration changes to it. As I had no need to recover the old password, I was looking for a way to simply replace the Administrator password with one of my choices. 

I came across this excellent post on the topic at 4sysops.com. Option 4, the Sticky Keys trick, worked for me and is exceptionally simple to do with guestfish in Fedora. Windows has a feature called Sticky Keys, part of its suite of accessibility features. As such, it’s available before login and critical to this method. In short, pressing a specific sequence of keys will invoke the Sticky Keys program. 

We will use Guestfish to temporarily replace that program with a command shell, use the command shell to change the Administrator password, log in, and then put everything back how it was. N.B. As pointed out in the above post, Windows uses your password to encrypt various bits of data, including the Windows Vault and passwords stored in IE. Changing the Administrator password using this mechanism will make that data permanently inaccessible. 

First, we assume we have local access to the disk image from our Fedora box and that libguestfs is installed. Also, note that this is an offline process, so the guest must be shut down at this point. Attempting to do this while the guest runs will result in data corruption.

# guestfish -i guest.img
Welcome to guestfish, the libguestfs filesystem interactive shell for editing virtual machine filesystems.
Type: 'help' for a list of commands 'man' to read the manual 'quit' to quit the shell
> mv /Windows/System32/sethc.exe /Windows/System32/sethc.exe.bak
> cp /Windows/System32/cmd.exe /Windows/System32/sethc.exe
> exit

You may find that the capitalization of the paths is different in your guest, but Guestfish’s tab completion should help you sort this out quite quickly. Start your guest again. When the login screen appears, press the SHIFT key 5 times. Instead of Sticky Keys, a command shell will be displayed:




Original post here

Thursday, April 22, 2021

Can't initialize iptables table filter and nat: Permission denied

The best solution will be to change the container image to have an updated iptables version, but in case you can't do that, follow the next steps.

Environment

  • Red Hat OpenShift Container Platform 4.6+

Issue

Executing iptables command in an application container fails with the following error.

 

[root@pod]# iptables -L iptables v1.8.4 (legacy): can't initialize iptables table `filter': Permission denied Perhaps iptables or your kernel needs to be upgraded.

[root@pod]# iptables -L -t nat iptables v1.8.4 (legacy): can't initialize iptables table `nat': Permission denied Perhaps iptables or your kernel needs to be upgraded.

Resolution

Add the needed capabilities and match the SELinux denied context on audit logs on pod.spec.containers[0].securityContext.

spec: containers: securityContext: privileged: false capabilities: drop: ["all"] add: ["NET_ADMIN", "NET_RAW", "NET_BIND_SERVICE"] seLinuxOptions: user: "system_u" role: "system_r" type: "container_t" level: "s0:c981,c991"

Diagnostic Steps

  1. Find the worker node from where the pod is running.
  2. Connect to the worker node.
  3. Tail audit log.
  4. Initialize a bash session on the pod.
  5. Execute iptables command.
  6. Wait for iptables denial error on audit log.

[root@worker] # tail -f /var/logs/audit/audit.log ...[ SNIP ]... type=AVC msg=audit(1618591176.860:2303): avc: denied { module_request } for pid=912615 comm="iptables" kmod="iptable_filter" scontext=system_u:system_r:container_t:s0:c981,c991 tcontext=system_u:system_r:kernel_t:s0 tclass=system permissive=0 type=AVC msg=audit(1618591176.860:2304): avc: denied { module_request } for pid=912615 comm="iptables" kmod="iptable_filter" scontext=system_u:system_r:container_t:s0:c981,c991 tcontext=system_u:system_r:kernel_t:s0 tclass=system permissive=0 ...[ SNIP ]...