CVE-2020-3837 : Detail

CVE-2020-3837

7.8
/
High
Overflow
5.83%V4
Local
2020-02-27
20h45 +00:00
2025-01-29
17h40 +00:00
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CVE Descriptions

A memory corruption issue was addressed with improved memory handling. This issue is fixed in iOS 13.3.1 and iPadOS 13.3.1, macOS Catalina 10.15.3, tvOS 13.3.1, watchOS 6.1.2. An application may be able to execute arbitrary code with kernel privileges.

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-787 Out-of-bounds Write
The product writes data past the end, or before the beginning, of the intended buffer.

Metrics

Metrics Score Severity CVSS Vector Source
V3.1 7.8 HIGH CVSS:3.1/AV:L/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.

Local

The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities.

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.

 nvd@nist.gov
V2 9.3 AV:N/AC:M/Au:N/C:C/I:C/A:C nvd@nist.gov

CISA KEV (Known Exploited Vulnerabilities)

Vulnerability name : Apple Multiple Products Memory Corruption Vulnerability

Required action : Apply updates per vendor instructions.

Known To Be Used in Ransomware Campaigns : Unknown

Added : 2022-06-26 22h00 +00:00

Action is due : 2022-07-17 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 : 48035

Publication date : 2020-02-09 23h00 +00:00
Author : Google Security Research
EDB Verified : Yes

While investigating possible shared memory issues in AGXCommandQueue::processSegmentKernelCommand(), I noticed that the size checks used to parse the IOAccelKernelCommand in IOAccelCommandQueue2::processSegmentKernelCommand() are incorrect. The IOAccelKernelCommand contains an 8-byte header consisting of a command type and size, followed by structured data specific to the type of command. When verifying that the size of the IOAccelKernelCommand has enough data for the specific command type, it appears that the check excludes the size of the 8-byte header, meaning that processSegmentKernelCommand() will parse up to 8 bytes of out-of-bounds data. Normally I wouldn't consider this very security-relevant. However, command type 2 corresponds to kIOAccelKernelCommandCollectTimeStamp, which actually *writes* into the OOB memory rather than just parsing data from it. (The IOAccelKernelCommand is being parsed from shared memory, so the write is visible to userspace.) This makes it possible to overwrite the first 1-8 bytes of the subsequent page of memory with timestamp data. The attached POC should trigger the issue on iOS 13. Tested on iPod9,1 17B111. I haven't tested on macOS, but it looks like the issue is present there as well. I'll also tack on to this issue that on the whole AGXCommandQueue seems to do a poor job of treating shared memory as volatile, and I suspect that there are further issues here that are worth looking into. For example, when IOAccelKernelCommand's type is 0x10000, AGXCommandQueue::processSegmentKernelCommand() does not use the fourth parameter (which points to the end of the IOAccelKernelCommand as parsed by IOAccelCommandQueue2::processSegmentKernelCommands()) except when passing it to IOAccelCommandQueue2::processSegmentKernelCommand(), instead double-fetching the command size from shared memory to verify that all the command data is in-bounds. Thus, I believe it's possible to make AGXCommandQueue::processSegmentKernelCommand() parse out-of-bounds data, although I have not found a way to turn this into an interesting exploitation primitive. I don't think the shared memory issues are isolated to this function either. For example, there used to be much more readily exploitable double-fetches in AGXAllocationList2::initWithSharedResourceList(), although these were fixed sometime between 16A5288q and 16G77. Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/48035.zip

Products Mentioned

Configuraton 0

Apple>>Ipados >> Version To (excluding) 13.3.1

Apple>>Iphone_os >> Version To (excluding) 13.3.1

Apple>>Mac_os_x >> Version To (excluding) 10.15.3

Apple>>Tvos >> Version To (excluding) 13.3.1

Apple>>Watchos >> Version To (excluding) 6.1.2

References