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PHTN-30-000031 - The Photon operating system must require authentication upon booting into single-user and maintenance modes.

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Information

If the system does not require authentication before it boots into single-user mode, anyone with console access to the system can trivially access all files on the system. GRUB2 is the boot loader for Photon OS and can be configured to require a password to boot into single-user mode or make modifications to the boot menu.

Note: Photon does not support building grub changes via grub2-mkconfig.

Solution

At the command line, run the following command:

# grub2-mkpasswd-pbkdf2

Enter a secure password and ensure this password is stored for break-glass situations. The vCenter root account cannot be recovered without knowing this separate password. Copy the resulting encrypted string.

An example string is below:

grub.pbkdf2.sha512.10000.983A13DF3C51BB2B5130F0B86DDBF0DEA1AAF766BD1F16B7840F79CE3E35494C4B99F505C99C150071E563DF1D7FE1F45456D5960C4C79DAB6C49298B02A5558.5B2C49E12D43CC5A876F6738462DE4EFC24939D4BE486CDB72CFBCD87FDE93FBAFCB817E01B90F23E53C2502C3230502BC3113BE4F80B0AFC0EE956E735F7F86

Navigate to and open:

/boot/grub2/grub.cfg

Find the line that begins with 'set rootpartition'. Below this line, paste the following on its own line:

set superusers='root'

Below this, paste the following, substituting the encrypted string from the steps above:

password_pbkdf2 root <YOUR-LONG-STRING-FROM-ABOVE>

Photon ships with one menuentry block by default. Copy that entire block and paste it right below itself.

Example:
menuentry 'Photon' {
 linux '/'$photon_linux root=$rootpartition net.ifnames=0 $photon_cmdline coredump_filter=0x37 consoleblank=0
 if [ '$photon_initrd' ]; then
 initrd '/'$photon_initrd
 fi
}
menuentry 'Photon' {
 linux '/'$photon_linux root=$rootpartition net.ifnames=0 $photon_cmdline coredump_filter=0x37 consoleblank=0
 if [ '$photon_initrd' ]; then
 initrd '/'$photon_initrd
 fi
}

Modify the first menuentry block to add the '--unrestricted' option as follows:

menuentry 'Photon' --unrestricted {

Modify the second menuentry block to add the allowed user as follows:

menuentry 'Recover Photon' --users root {

This concludes the fix. To verify, here is an example grub.cfg snippet:

...
set rootpartition=PARTUUID=326e5b0f-42fb-471a-8209-18964c4a2ed3
set superusers='root'
password_pbkdf2 root grub.pbkdf2.sha512.10000.983A13DF3C51BB2B5130F0B86DDBF0DEA1AAF766BD1F16B7840F79CE3E35494C4B99F505C99C150071E563DF1D7FE1F45456D5960C4C79DAB6C49298B02A5558.5B2C49E12D43CC5A876F6738462DE4EFC24939D4BE486CDB72CFBCD87FDE93FBAFCB817E01B90F23E53C2502C3230502BC3113BE4F80B0AFC0EE956E735F7F86

menuentry 'Photon' --unrestricted {
 linux '/'$photon_linux root=$rootpartition net.ifnames=0 $photon_cmdline coredump_filter=0x37 consoleblank=0
 if [ '$photon_initrd' ]; then
 initrd '/'$photon_initrd
 fi
}

menuentry 'Recover Photon' --users root {
 linux '/'$photon_linux root=$rootpartition net.ifnames=0 $photon_cmdline coredump_filter=0x37 consoleblank=0
 if [ '$photon_initrd' ]; then
 initrd '/'$photon_initrd
 fi
}

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_VMW_vSphere_7-0_Y23M07_STIG.zip

Item Details

References: CAT|I, CCI|CCI-000213, Rule-ID|SV-256508r887198_rule, STIG-ID|PHTN-30-000031, Vuln-ID|V-256508

Plugin: Unix

Control ID: a28d20e17c07296673c2e9c1faff05ae68e3a4ba5ccf7752ffc040496bba8971