5 ms·

From the FreeBSD man for date Only the superuser may set the date, and if the system securelevel (see securelevel(7)) is greater than 1, the time may not b

From the FreeBSD man for date Only the superuser may set the date, and if the system securelevel (see securelevel(7)) is greater than 1, the time may not be changed by more than 1 second. EDIT: so you need to be root anyway or have root access to change the date.

nwh 14y ago
Users on MacOS can change the time without root access.
- simias 14y ago
  Are you sure? If it is it sounds like a possible security issue. Time is pretty sensitive as soon as certificates are involved. Many auth systems assume the clock is properly synchronized across the system. If that's true IMO that's the security issue, not the arguably strange behaviour of sudo in a situation that should never occur.
  - dazzawazza 14y ago
    well from the terminal $ date 010101011970 date: bind: Permission denied date: settimeofday (timeval): Operation not permitted [15:45:41][dazza@imac.internal:~] From System Preferences you can indeed set the date back to 1970: $ date Fri 2 Jan 1970 00:56:44 BST [00:56:44][dazza@imac.internal:~] but there is a little lock that you might need to unlock (with a user password). This does seem like a security issue on OSX.
    - adestefan 14y ago
      That little lock icon is the same as running sudo from the command line. If the user is listed as an Administrator, then they're also able to sudo.
    - pschastain 14y ago
      Changing back 01/01/1970 via Date & Time preferences doesn't need authentication, but the exploit still didn't work, at least for me.
      - acdha 14y ago
        > Changing back 01/01/1970 via Date & Time preferences doesn't need authentication This is not true but it can be confusing if you've authenticated at all recently due to a grace period like sudo's.
        nwh 14y ago
        I've never unlocked that panel, and I've rebooted recently, and still didn't need authentication. Are you sure that's as right?
        adestefan 14y ago
        The authentication for changing things via the System Preferences system is independent of sudo and "sticks" across reboots.
        glitch 14y ago
        Is your account an Administrator account? Normal users are just Standard accounts and not Administrators.
- rplnt 14y ago
  System time or what is displayed to the user? Because they are two different things on some systems.
- deleted 14y ago
  [deleted]
- kgo 14y ago
  But most of the time, someone using MacOS has physical access to the box. They can always just boot up as single user and BOOM root: http://support.apple.com/kb/ht1492 http://support.apple.com/kb/ht1492
- adestefan 14y ago
  This is absolutely not true. You must be listed as an Administrator to change system time. If you're an Administrator, then your account is also included in the admin group which means you have full sudo access anyway.
- glitch 14y ago
  As far as I tested in the Date and Time preference pane,... Users enabled as an Administrator, yes. Standard users, no. `date` still behaves as one expects.
frankc 14y ago
Would this work with an LD_PRELOAD of libfaketime?
- throwaway2048 14y ago
  env_reset If set, sudo will run the command in a minimal environment containing the TERM, PATH, HOME, MAIL, SHELL, LOGNAME, USER, USERNAME and SUDO_* variables. Any variables in the caller's environment that match the env_keep and env_check lists are then added, followed by any variables present in the file specified by the env_file option (if any). The default contents of the env_keep and env_check lists are displayed when sudo is run by root with the -V option. If the secure_path option is set, its value will be used for the PATH environment variable. This flag is on by default. Also this would open up an entire vector of arbitrary command execution attacks if it was allowed. Also, you can not use LD_PRELOAD on sudo itself, as it is disabled for setuid binaries.

nwh 14y ago

Users on MacOS can change the time without root access.

simias 14y ago
Are you sure? If it is it sounds like a possible security issue. Time is pretty sensitive as soon as certificates are involved. Many auth systems assume the clock is properly synchronized across the system. If that's true IMO that's the security issue, not the arguably strange behaviour of sudo in a situation that should never occur.
- dazzawazza 14y ago
  well from the terminal $ date 010101011970 date: bind: Permission denied date: settimeofday (timeval): Operation not permitted [15:45:41][dazza@imac.internal:~] From System Preferences you can indeed set the date back to 1970: $ date Fri 2 Jan 1970 00:56:44 BST [00:56:44][dazza@imac.internal:~] but there is a little lock that you might need to unlock (with a user password). This does seem like a security issue on OSX.
  - adestefan 14y ago
    That little lock icon is the same as running sudo from the command line. If the user is listed as an Administrator, then they're also able to sudo.
  - pschastain 14y ago
    Changing back 01/01/1970 via Date & Time preferences doesn't need authentication, but the exploit still didn't work, at least for me.
    - acdha 14y ago
      > Changing back 01/01/1970 via Date & Time preferences doesn't need authentication This is not true but it can be confusing if you've authenticated at all recently due to a grace period like sudo's.
      - nwh 14y ago
        I've never unlocked that panel, and I've rebooted recently, and still didn't need authentication. Are you sure that's as right?
        adestefan 14y ago
        The authentication for changing things via the System Preferences system is independent of sudo and "sticks" across reboots.
        glitch 14y ago
        Is your account an Administrator account? Normal users are just Standard accounts and not Administrators.
rplnt 14y ago
System time or what is displayed to the user? Because they are two different things on some systems.
deleted 14y ago
[deleted]
kgo 14y ago
But most of the time, someone using MacOS has physical access to the box. They can always just boot up as single user and BOOM root: http://support.apple.com/kb/ht1492 http://support.apple.com/kb/ht1492
adestefan 14y ago
This is absolutely not true. You must be listed as an Administrator to change system time. If you're an Administrator, then your account is also included in the admin group which means you have full sudo access anyway.
glitch 14y ago
As far as I tested in the Date and Time preference pane,... Users enabled as an Administrator, yes. Standard users, no. `date` still behaves as one expects.

frankc 14y ago

Would this work with an LD_PRELOAD of libfaketime?

throwaway2048 14y ago
env_reset If set, sudo will run the command in a minimal environment containing the TERM, PATH, HOME, MAIL, SHELL, LOGNAME, USER, USERNAME and SUDO_* variables. Any variables in the caller's environment that match the env_keep and env_check lists are then added, followed by any variables present in the file specified by the env_file option (if any). The default contents of the env_keep and env_check lists are displayed when sudo is run by root with the -V option. If the secure_path option is set, its value will be used for the PATH environment variable. This flag is on by default. Also this would open up an entire vector of arbitrary command execution attacks if it was allowed. Also, you can not use LD_PRELOAD on sudo itself, as it is disabled for setuid binaries.