PARSEC Technical Information

If you've searched for OpenVMS vulnerabilities at either the https://cve.mitre.org/ or https://nvd.nist.gov/ you may have run across CVE-2017-17482

Per the Nist site, this Vulnerability and Exposure states the following ¹⁾

An issue was discovered in OpenVMS through V8.4-2L2 on Alpha and through V8.4-2L1 on IA64, and VAX/VMS 4.0 and later. A malformed DCL command table may result in a buffer overflow allowing a local privilege escalation when a non-privileged account enters a crafted command line. This bug is exploitable on VAX and Alpha and may cause a process crash on IA64. Software was affected regardless of whether it was directly shipped by VMS Software, Inc. (VSI), HPE, HP, Compaq, or Digital Equipment Corporation.

• Alpha OpenVMS V8.4 systems should have this patch installed: VMS84A_DCL-V0200 Contact HPE for the patch
• Itanium OpenVMS V8.4 systems should have this patch installed: VMS84I_DCL-V0200 Contact HPE for the patch

Alpha customers running VSI OpenVMS V8.4-2L1 or VSI OpenVMS V8.4-2L2 for Alpha, contact VSI support to obtain the appropriate patch version.

IA64 customers running VSI OpenVMS V8.4-1H1, VSI OpenVMS V8.4-2, or VSI OpenVMS V8.4-2L1, if you have a support contract with HPE for your version, contact HPE customer support to obtain the patch; otherwise, contact VSI support.²⁾

For VAX, Alpha, and Integrity users unable to patch OpenVMS, here are best practices to better protect your systems from the vulnerability.

• Practice good user account control. The attacker must be able to log into the OpenVMS system to exploit the vulnerability.

• Disable user access to the DCL “SET COMMAND”. Most unprivileged users should never need access to this function. As HPE explains:

The vulnerability is in the CDU.EXE image, which is installed with CMEXEC privilege, and a workaround is to remove privileges from the image. This can be done by editing the files SYS$MANAGER:VMSIMAGES.DAT plus the master VMS$IMAGES_MASTER.DAT and then rebooting.

The relevant lines look like this (this may vary between versions of OpenVMS):

$ search sys$manager:vms$images_master.dat,vmsimages.dat cdu
******************************
SYS$COMMON:[SYSMGR]VMS$IMAGES_MASTER.DAT;1
sys$system:cdu /open /header /priv=(cmexec) !
******************************
SYS$SYSROOT:[SYSMGR]VMSIMAGES.DAT;1
SYS$SYSTEM:CDU /OPEN /HEADER /PRIV=(CMEXEC) ! 1/0/

The workaround would be to simply remove the “/PRIV=(CMEXEC)” qualifier from these lines. This prevents a non-privileged user from using the DCL “SET COMMAND”.

Along the same vein, the system DCL table could be patched to remove the COMMAND option from the SET command.