PING : OPENVIEW OMNIBACK II VULNERABILITY : RECOMMENDATIONS
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SECURITY VULNERABILITY WITH HP OPENVIEW OMNIBACK II A. Background B. Fixing the problem C. Recommendations D. Subscribe to receive future HP Security Bulletins E. Report new security vulnerabilities |
With all of the new patches two of the three vulnerabilities have been fixed. Solving or minimizing the third one requires additional administrative effort as described below.
NOTE: Hewlett-Packard Company will not be liable for any consequences to any customer resulting from that customer's choice of one of the three options to follow. We recommend option E1 (DISABLE pre/post-exec), but only you can determine if this is appropriate for your environment.
OmniBack allows execution of pre-/post-exec commands as root on any client system.
After installing the above mentioned patches and pushing the OB Disk Agent module to all OB systems there are two mechanisms available within OB that can be combined in order to provide a higher level of security:
Options:
E1 - DISABLE pre/post-exec
E2 - RESTRICT pre/post-exec to the lbin directory
E3 - pre/post-exec completely ENABLED
NOTE: Option E3 is the current mode of operation. It has the
current level of vulnerability and is not recommended.
a. OB 2.55 - You can enable the OB internal security
mechanism to restrict ACCESS to OB inet for all
systems in a cell.
b. OB 2.1 - You can use the HP-UX built-in inetd.sec
in order to restrict client ACCESS to certain
systems only.
Option A2 is the current mode of operation with or without
the patch. It has the current level of vulnerability and
is NOT recommended. (It is the default setting with the patch).
The remaining risks, if you do not follow this recommendation, are described in the following matrix:
Option E1 Option E2 Option E3
+-----------------+-----------------+----------------+
| DISABLE | RESTRICT | ENABLE |
| pre/post-exec | pre/post-exec to| pre/post-exec |
| (*) | lbin directory | completely |
| | (*) | (*) |
+------------+-----------------+-----------------+----------------+
| Option A1: | SECURE | users on Cell | users on Cell |
| | | Manager system | Manager system |
| a. ENABLE | | potentially can | potentially can|
| OmniBack II| | execute | execute |
| security | | pre/post-exec | pre/post-exec |
| | | commands in | any command |
| b. use | | lbin directory | as root on any |
| inetd.sec | | as root on any | system in cell |
| (*) | | system in cell | |
+------------+-----------------+-----------------+----------------+
| Option A2: | SECURE | users on ANY | users on ANY |
| | | system | system |
| DISABLE | | potentially can | potentially can|
| OmniBack II| | execute | execute |
| security | | pre/post-exec | pre/post-exec |
| (*) | | commands in | any command |
| | | lbin directory | as root on any |
| | | as root on any | system in cell |
| | | system in cell | |
+------------+-----------------+-----------------+----------------+
(*) A more detailed description follows below.
Option E1 (DISABLE pre/post-exec) and Option E2 (RESTRICT pre/post-exec):In order to disable or restrict execution of pre/post exec scripts, add the variables OB2REXECOFF and/or OB2OEXECOFF into the omnirc. file on UNIX systems, or as REG_SZ type to the Windows NT/95 registry:
The location of the omnirc. file is:
Permissions for the omnirc. file are 600 (read/write for owner)
OB2REXECOFF=0 (not disabled, default)
=1 (remote pre/post-exec disabled on the client)
NOTE: REMOTE pre/post-exec executables must reside in LBIN (**)
OB2OEXECOFF=0 (not disabled, default)
=1 (OBJECT pre/post-exec disabled on the client)
=2 (OBJECT pre/post-exec restricted to executables
in LBIN (**)
(**) LBIN is:
- /opt/omni/lbin on HP-UX 10.X and 11.0 systems
- /usr/omni/lbin on other UNIX systems
- OmniBack\bin on Windows systems
On Windows the values are the same as on UNIX, but the Windows clients read OB2REXECOFF and OB2OEXECOFF from the registry.
To set these variables, add them as values to the following key
for OBII versions A.02.30 and A.02.55:
HKEY_LOCAL_MACHINE\SOFTWARE\Hewlett-Packard\OpenView\OmniBackII\
Common\Parameters
or to the following key for version A.02.10:
HKEY_LOCAL_MACHINE\SOFTWARE\Hewlett-Packard\OpenView\OmniBackII\
BackUp
If the use of the pre/post exec scripts shall be restricted to the executables in LBIN (see **above), the system administrator must set OB2OEXECOFF=2 and move ALL pre/post exec scripts to LBIN. This prevents an ordinary user from executing his own scripts. To configure pre/post scripts to run, ordinary users must now contact the system manager to move these scripts to LBIN AND chmod them to be only 555. The scripts can be owned by the user, but the directory executable permissions automatically take precedence.
NOTE: Under this mode, any remaining root owned pre/post scripts should be carefully scrutinized for operations that might be undesirable if executed unexpectedly by malicious users.
NOTE: With the restriction to run pre/post-execs from LBIN only, it is still possible to execute commands that cannot be moved to LBIN by placing a wrapper script into LBIN that calls the command.
Example:
#!/bin/sh
cd /opt/myapp/bin # change dir
./shutdown_myapp.sh # execute command
return $? # pass return value
CAUTION: - The wrapper transfers the potential vulnerability to the user's script (/opt/myapp/bin/shutdown_myapp.sh in the example). A malicious user would only need access to the user's account to modify the script called by the wrapper.
Option A1 (enable OB security):
a. OB 2.55
In addition restrict access to the OB systems in the cell. This limits the range of users that have the possibility to execute pre-/post-execs on the cell's systems.
A quick way to do this is to enable the OmniBack II built-in security mechanism which restricts access to the client systems to the cell manager and other specified systems. Other systems that are not configured in OmniBack II security will not be able to connect to the OmniBack II inet running on the system. It can be managed from the GUI or by modifying files (on UNIX) or registry entries (on Windows).
Motif GUI procedure:
- open "Install"
- select "Edit"/"Add access limit to hosts in the cell..."
Manual procedure:
- create the file "allow_hosts" on all client systems in the
cell. The location is:
HP-UX 10.X and 11.0: /etc/opt/omni/cell/allow_hosts
other Unix: /usr/omni/config/cell/allow_hosts
Novell: sys:\usr\omni\config\cell\allow_hosts
Permissions for this file are 600 (read/write for owner)
On Windows systems this content is not in a file but in the registry:
HKEY_LOCAL_MACHINE\SOFTWARE\Hewlett-Packard\OpenView\
OmniBackII\Common\allow_hosts
OB inet reads this file on startup. If this file is present, no other system than the Cell Manager will be allowed to connect through OB inet.
If you need to allow other systems to connect to OmniBack clients through inet, add them (line by line) to the allow_hosts file on the corresponding host.
For example:
NOTE: This OB built in security does not apply to versions prior to OB 2.50.
b. OB 2.1
HP-UX has a built-in security mechanism that can be used to restrict access to certain services based on IP addresses. The OB 2.1 GUI can be used in order to enable this security on all HP-UX systems in the cell.
If you want to enable inetd.sec security on selected systems only, please use the manual procedure:
The inetd.sec file is located in /var/adm (HP-UX 10.x and 11.x) and in /usr/adm (HP-UX 9.x).
Example: In order to restrict access to the OmniBack service to all hosts with an IP address beginning with 15.136.120, add the following line to inetd.sec:
omni allow 15.136.120.* 127.0.0.1
(the 127.0.0.1 is required to let the system access itself)
After modifying inetd.sec, you need to restart inetd on the system.
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