Advisory Details

November 20th, 2017

Apple macOS nsurlstoraged Integer Overflow Privilege Escalation Vulnerability

ZDI-17-925
ZDI-CAN-4927

CVE ID CVE-2017-13833
CVSS SCORE 4.4, AV:L/AC:M/Au:N/C:P/I:P/A:P
AFFECTED VENDORS Apple
AFFECTED PRODUCTS macOS
VULNERABILITY DETAILS


This vulnerability allows local attackers to escalate privileges on vulnerable installations of Apple macOS. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.

The specific flaw exists within the nsurlstoraged service. The issue results from the lack of proper validation of a reference count, which can result in an integer overflow when incrementing it. An attacker can leverage this vulnerability to escalate privileges under the context of the current service.
ADDITIONAL DETAILS Apple has issued an update to correct this vulnerability. More details can be found at:
https://support.apple.com/en-us/HT208112
DISCLOSURE TIMELINE
  • 2017-06-22 - Vulnerability reported to vendor
  • 2017-11-20 - Coordinated public release of advisory
CREDIT Niklas Baumstark and Samuel Gro
BACK TO ADVISORIES