Yahoo has awarded thousands of dollars to a couple of researchers who managed to find serious vulnerabilities in the company’s systems. The bug bounty hunters published blog posts over the weekend describing their findings.
An expert who uses the online moniker “Th3G3nt3lman” said he received $5,500 from Yahoo for a remote code execution vulnerability in Apache Struts 2. The white hat hacker discovered the flaw on a Yahoo subdomain hosting a login page for a Selligent marketing product.
The security hole is CVE-2017–5638, a Struts 2 vulnerability that malicious actors started exploiting in March, shortly after a patch was released. The weakness has been found to affect the products and systems of many companies, including Cisco, VMware and AT&T.
According to Th3G3nt3lman, the initial exploit published for CVE-2017–5638 did not work on the Yahoo website, but he found a different exploit on Twitter – one that can bypass web application firewalls (WAFs) – that could have been used to achieve remote code execution.
Cryptography and information security enthusiast Sam Curry also published a blog post over the weekend describing a critical vulnerability in a Yahoo-owned system. Unlike Th3G3nt3lman, who found the RCE flaw on a Yahoo domain, Curry and a bounty hunter known online as “dawgyg” discovered a bug in the video streaming website SnackTV, which Yahoo took over in late 2014 with the acquisition of Media Group One.
In addition to some low severity issues, Curry and dawgyg noticed that the SnackTV website had been affected by the ImageMagick vulnerability known as ImageTragick. The flaw in the popular image processing suite was disclosed in May 2016, when it had already been exploited in the wild.
The hackers noticed that the server in question was not vulnerable to the generic ImageTragick attack, but after some tweaking they managed to get an exploit to work and achieved command injection. Yahoo patched the flaw within two days after learning of its existence and awarded the experts $3,000.
Yahoo has been informed of several ImageMagick vulnerabilities, and several months ago the company decided to stop using the library after a researcher discovered a critical flaw that could have been exploited to obtain sensitive data belonging to Yahoo Mail users.
Curry reported his findings to Yahoo last month, which suggests that while Yahoo removed ImageMagick from some services, the software is still present on some of its websites.
This was not the only vulnerability disclosed by Curry to Yahoo in recent weeks. In May, he published two other blog posts describing cross-site scripting (XSS) and other weaknesses that earned him a total of more than $2,000.