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CVE-2016-4669 : Detail

CVE-2016-4669

7.8
/
HIGH
A03-Injection
0.04%V3
Local
2017-02-20 07:35 +00:00
2020-08-14 20:06 +00:00
CVE.org
NVD

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Descriptions

An issue was discovered in certain Apple products. iOS before 10.1 is affected. macOS before 10.12.1 is affected. tvOS before 10.0.1 is affected. watchOS before 3.1 is affected. The issue involves the "Kernel" component. It allows local users to execute arbitrary code in a privileged context or cause a denial of service (MIG code mishandling and system crash) via unspecified vectors.

Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-20 Improper Input Validation
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

Metrics

Metric 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 : 40654

Publication date : 2016-10-30 23:00 +00:00
Author : Google Security Research
EDB Verified : Yes

Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=882 mach_ports_register is a kernel task port MIG method. It's defined in MIG like this: routine mach_ports_register( target_task : task_t; init_port_set : mach_port_array_t = ^array[] of mach_port_t); Looking at the generated code for this we notice something kinda weird; here's the mach message structure which actually gets sent: typedef struct { mach_msg_header_t Head; // start of the kernel processed data mach_msg_body_t msgh_body; mach_msg_ool_ports_descriptor_t init_port_set; // end of the kernel processed data NDR_record_t NDR; mach_msg_type_number_t init_port_setCnt; } Request __attribute__((unused)); The message contains an OOL ports descriptor, which is expected, but also contains a separate init_port_setCnt value even though the ool_ports_descriptor_t already has the correct length of the descriptor. When the kernel process this ool ports descriptor in ipc_kmsg_copyin_ool_ports_descriptor it will kalloc a buffer large enough for all the ports and then copyin and convert them all. It does this using the init_port_set.count value, not init_port_setCnt. The generated MIG code however calls mach_ports_register like this: OutP->RetCode = mach_ports_register(target_task, (mach_port_array_t)(In0P->init_port_set.address), In0P->init_port_setCnt); without verifying that In0P->init_port_setCnt is equal to init_port_set.count. This means that when we reach mach_ports_register lots of stuff goes wrong: kern_return_t mach_ports_register( task_t task, mach_port_array_t memory, <-- points to kalloc'ed buffer mach_msg_type_number_t portsCnt) <-- completely controlled, not related to size of kalloc'ed buffer { ipc_port_t ports[TASK_PORT_REGISTER_MAX]; unsigned int i; if ((task == TASK_NULL) || (portsCnt > TASK_PORT_REGISTER_MAX) || (portsCnt && memory == NULL)) return KERN_INVALID_ARGUMENT; <-- portsCnt must be >=1 && <= 3 for (i = 0; i < portsCnt; i++) ports[i] = memory[i]; <-- if we only sent one OOL port but set portsCnt >1 this will read a mach_port_t (a pointer) out of bounds for (; i < TASK_PORT_REGISTER_MAX; i++) ports[i] = IP_NULL; itk_lock(task); if (task->itk_self == IP_NULL) { itk_unlock(task); return KERN_INVALID_ARGUMENT; } for (i = 0; i < TASK_PORT_REGISTER_MAX; i++) { ipc_port_t old; old = task->itk_registered[i]; task->itk_registered[i] = ports[i]; ports[i] = old; } itk_unlock(task); for (i = 0; i < TASK_PORT_REGISTER_MAX; i++) if (IP_VALID(ports[i])) ipc_port_release_send(ports[i]); <-- this can decrement the ref on a pointer which was read out of bounds if we call this function multiple times if (portsCnt != 0) kfree(memory, (vm_size_t) (portsCnt * sizeof(mach_port_t))); <-- this can call kfree with the wrong size return KERN_SUCCESS; } For this PoC I've patched the MIG generated code to always only send one OOL mach port but still set init_port_setCnt to a controlled value - you should see a kernel panic decrementing an invalid reference or something like that. This bug however could be exploited quite nicely to cause a mach_port_t UaF which could have all kinds of fun consequences (getting another task's task port for example!) tested on OS X 10.11.6 (15G31) on MacBookPro10,1 Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/40654.zip

Products Mentioned

Configuraton 0

Apple>>Iphone_os >> Version To (excluding) 10.1

Configuraton 0

Apple>>Mac_os_x >> Version To (excluding) 10.12.1

Configuraton 0

Apple>>Tvos >> Version To (excluding) 10.0.1

Configuraton 0

Apple>>Watchos >> Version To (excluding) 3.1

References

https://support.apple.com/HT207271
Tags : x_refsource_CONFIRM
http://www.securitytracker.com/id/1037086
Tags : vdb-entry, x_refsource_SECTRACK
http://www.securityfocus.com/bid/93849
Tags : vdb-entry, x_refsource_BID
https://support.apple.com/HT207269
Tags : x_refsource_CONFIRM
https://support.apple.com/HT207270
Tags : x_refsource_CONFIRM
https://support.apple.com/HT207275
Tags : x_refsource_CONFIRM
https://www.exploit-db.com/exploits/40654/
Tags : exploit, x_refsource_EXPLOIT-DB

More information
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