Flaw in SAP Firm's XSS Filter Exposed Many Sites to Attacks

Roughly one hundred websites were exposed to cross-site scripting (XSS) attacks because an XSS filter used on some of their web pages could have been easily bypassed, a researcher reported on Sunday.

Ashar Javed, a security researcher who specializes in finding tricky XSS vulnerabilities,identified a reflected XSS flaw on a website used by Germany-based enterprise software maker SAP to list jobs available within the company.

While the affected page was protected by an XSS filter to prevent attacks, the expert discovered that developers had failed to escape certain strings, such as </ and ', when sanitizing user input. This oversight could have allowed attackers to inject specially crafted XSS payloads into the website.

After conducting some tests, Javed discovered that </ could not be used for XSS attacks since the "</script>" string was blocked, but the single quotation mark had been used by developers for “if” conditions, allowing the use of XSS payloads such as ‘-confirm(1)-’.

In this example, the JavaScript “confirm” function is used to display a dialog box containing the message “1” along with OK and Cancel buttons. However, the expert told SecurityWeekthat other functions could have been used as well.

After reporting his findings to SAP at the software giant’s Product Security Expert Summit in March, Javed learned that the flawed XSS filter belongs to SuccessFactors, a SAP-owned company that provides cloud-based human capital management solutions.

The expert identified the buggy XSS filter on roughly 100 websites, many of which belong to high profile companies. Javed believes the filter is part of SuccessFactors’ product, which is also suggested by the fact that the vulnerable component is present on the jobs/careers domains of the impacted sites.

The vulnerability was addressed roughly three months after it was reported to SAP. The company acknowledged the security researcher’s work in July.

Javed says he has also identified a series of flaws in SAP Enterprise Portal, which he plans on disclosing after they are resolved by the vendor.

Last month, the researcher reported finding an XSS vulnerability in YouTube Gaming, a gaming-focused video website launched this summer by YouTube. The expert reported his findings to Google and was awarded more than $3,000 for his work.