CVE-2016-2494 : Detail

CVE-2016-2494

7.8
/
High
A01-Broken Access Control
0.3%V3
Local
2016-06-12
23h00 +00:00
2016-11-28
19h57 +00:00
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CVE Descriptions

Off-by-one error in sdcard/sdcard.c in Android 4.x before 4.4.4, 5.0.x before 5.0.2, 5.1.x before 5.1.1, and 6.x before 2016-06-01 allows attackers to gain privileges via a crafted application, as demonstrated by obtaining Signature or SignatureOrSystem access, aka internal bug 28085658.

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-264 Category : Permissions, Privileges, and Access Controls
Weaknesses in this category are related to the management of permissions, privileges, and other security features that are used to perform access control.

Metrics

Metrics 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

 [email protected]
V2 9.3 AV:N/AC:M/Au:N/C:C/I:C/A:C [email protected]

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 : 39921

Publication date : 2016-06-09 22h00 +00:00
Author : Google Security Research
EDB Verified : Yes

Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=798 Android: Stack-buffer-overflow in /system/bin/sdcard There's an integer overflow issue in get_node_path_locked, which results in a buffer overflow. For all of the calling paths, this is going to overflow a stack buffer in the parent function: static ssize_t get_node_path_locked(struct node* node, char* buf, size_t bufsize) { const char* name; size_t namelen; if (node->graft_path) { name = node->graft_path; namelen = node->graft_pathlen; } else if (node->actual_name) { name = node->actual_name; namelen = node->namelen; } else { name = node->name; namelen = node->namelen; } // when bufsize == namelen + 1 if (bufsize < namelen + 1) { return -1; } ssize_t pathlen = 0; if (node->parent && node->graft_path == NULL) { // bufsize - namelen - 2 overflows to SIZE_MAX pathlen = get_node_path_locked(node->parent, buf, bufsize - namelen - 2); if (pathlen < 0) { return -1; } buf[pathlen++] = '/'; } memcpy(buf + pathlen, name, namelen + 1); /* include trailing \0 */ return pathlen + namelen; } This can be triggered by a malicious app creating a directory structure in /sdcard with a total path length longer than PATH_MAX, which can be achieved by creating a directory heirarchy starting with several directories with short names and later renaming these parent directories to have longer names. See the attached POC, which can be run from the 'untrusted_app' selinux domain. It appears that the overflow is close enough to the bottom of the stack that with a large overflow we can corrupt thread data that is used before the stack cookie is checked, suggesting that this issue is possibly exploitable despite the presence of stack cookies. (gdb) i r r0 0xb 11 r1 0x1 1 r2 0x41414199 1094795673 r3 0x41414141 1094795585 r4 0x80000000 2147483648 r5 0x0 0 r6 0xb6e40ec0 3068399296 r7 0xb6cbe860 3066816608 r8 0xb6e4930c 3068433164 r9 0xb6e3c594 3068380564 r10 0xbee4c9ac 3202664876 r11 0xb6943180 3063165312 r12 0xb6e3c908 3068381448 sp 0xb6cbe7a0 0xb6cbe7a0 lr 0xb6e1daad -1226712403 pc 0xb6e06ade 0xb6e06ade <pthread_getspecific(pthread_key_t)+34> cpsr 0x80070030 -2147024848 (gdb) x/10i $pc => 0xb6e06ade <pthread_getspecific(pthread_key_t)+34>: ldr r4, [r2, #100] ; 0x64 0xb6e06ae0 <pthread_getspecific(pthread_key_t)+36>: cmp r4, r1 0xb6e06ae2 <pthread_getspecific(pthread_key_t)+38>: bne.n 0xb6e06aec <pthread_getspecific(pthread_key_t)+48> 0xb6e06ae4 <pthread_getspecific(pthread_key_t)+40>: ldr r0, [r2, #104] ; 0x68 0xb6e06ae6 <pthread_getspecific(pthread_key_t)+42>: pop {r4, pc} 0xb6e06ae8 <pthread_getspecific(pthread_key_t)+44>: movs r0, #0 0xb6e06aea <pthread_getspecific(pthread_key_t)+46>: pop {r4, pc} 0xb6e06aec <pthread_getspecific(pthread_key_t)+48>: adds r0, #12 0xb6e06aee <pthread_getspecific(pthread_key_t)+50>: add.w r12, r3, r0, lsl #3 0xb6e06af2 <pthread_getspecific(pthread_key_t)+54>: movs r0, #0 (gdb) bt #0 0xb6e06ade in pthread_getspecific (key=11) at bionic/libc/bionic/pthread_key.cpp:160 #1 0xb6e1daac in je_tsd_wrapper_get () at external/jemalloc/include/jemalloc/internal/tsd.h:609 #2 je_tsd_get () at external/jemalloc/include/jemalloc/internal/tsd.h:609 #3 je_tsd_fetch () at external/jemalloc/include/jemalloc/internal/tsd.h:614 #4 imalloc_body (usize=<synthetic pointer>, tsd=<synthetic pointer>, size=4) at external/jemalloc/src/jemalloc.c:1401 #5 je_malloc (size=4) at external/jemalloc/src/jemalloc.c:1423 #6 0xb6f3bb3e in handle_open (fuse=0xbee478c8, hdr=0xbee4c984, req=<optimized out>, handler=<optimized out>) at system/core/sdcard/sdcard.c:1193 #7 0x41414140 in ?? () Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/39921.zip

Products Mentioned

Configuraton 0

Google>>Android >> Version 4.0

Google>>Android >> Version 4.0.1

Google>>Android >> Version 4.0.2

Google>>Android >> Version 4.0.3

Google>>Android >> Version 4.0.4

Google>>Android >> Version 4.1

Google>>Android >> Version 4.1.2

Google>>Android >> Version 4.2

Google>>Android >> Version 4.2.1

Google>>Android >> Version 4.2.2

Google>>Android >> Version 4.3

Google>>Android >> Version 4.3.1

Google>>Android >> Version 4.4

Google>>Android >> Version 4.4.1

Google>>Android >> Version 4.4.2

Google>>Android >> Version 4.4.3

Google>>Android >> Version 5.0

Google>>Android >> Version 5.0.1

Google>>Android >> Version 5.1

Google>>Android >> Version 5.1.0

Google>>Android >> Version 6.0

Google>>Android >> Version 6.0.1

References

https://www.exploit-db.com/exploits/39921/
Tags : exploit, x_refsource_EXPLOIT-DB