Bastion: Hack the box

Intrdouction

Target: 10.10.10.134 (Windows)

Kali: 10.10.16.65

In conclusion, Bastion is not a medium box. But it would be easier to solve this box with windows VM. Command VM may be a good choice. But it can be finished by kali.

Information enumeration

Firstly, detect the open ports:

From the open ports, it can be induced that the box may be a windows machine that opens ssh service. Then try to obtain the detailed services of these open ports:

Exploitation

There seem to be nothing special. For a normal box, http service will be the starting. For this box, we should try smb service for port 445. For smb service exploitation in kali, we choose to use smbmap, smbclient, enum4linux, etc. Let's try smbclient:

With smbclient, we can see the smb shares of this box without any password. Try to access the share by smbclient//10.10.10.134/sharename . But the three shares cannot be accessed except Backups .

Access to the share of Backups : smbclient//10.10.10.134/Backups :

There is a note.txt in the share:

It does is a hint for something useful in the exploitation. It is inconvenient to access files by smbclient, as you cannot browse the file directly. So try to mount the shared folder to kali:

Here, we can access the files directly. It may be a backup folder. After some exploration, we have found some interesting files.

VHD(virtual hard disk) files seem to be very interesting. According to the wiki, VHDisa file format which represents avirtualhard disk drive(HDD).Itmay contain whatisfound on a physical HDD,suchasdisk partitionsanda file system,whichinturn can contain filesandfolders.Itistypically usedasthe hard disk of avirtualmachine . So we may find more interesting contents in the VHD files. There are two vhd files, one is 37M, and the other is 5.1 G. The larger one seems to be attractive to us. But it will be inconvenient to download the whole vhd file. According to the discussions in the forum, the author has said that you don't have to download the vhd file. Try to mount the vhd file to kai:

The operation may cost some time if the network is not very stable. Then, the vhd file in mounted successfully. It seems to be an OS disk. There seem nothing special. Security Account Manager(SAM) is the database file in Windows which stores user passwords. Try to access the SAM files, samdump2 can be utilized to dump the hash.

From the dumped hash, the hash of L4mpje seems to be useful. We can access HashKiller to crack the hash.

We cracked it! As we know the box opens ssh service, so try to access ssh with the user of L4mpje. Of course, we are in.

Privilege escalation

After login with user L4mpje, we find that we have relatively limited permission. PrivEsc is often vulnerable to some specific software vulnerability. It is significant to see the program files of the box.

We can find an interesting folder mRemoteNG . It is an open source remote connections management tool. But there is a problem that the connections user information can be obtained by the config files. For this box, someone has created a tool to crack the password in this config file. The config file is store is the AppData folder.

It seems that the password of Administrator is stored in the XML file. Someone has created mremoteng-decrypt to crack the password. It is so convenient thanks to his awesome work.

Wow, we get the password of Administrator.

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