Dark Reading is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them.Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

Vulnerabilities / Threats

Filling Out Forms: Still a Dangerous Game

Despite upgrades and fixes, most browsers are still vulnerable to attacks via Web forms, researcher says

It may not sound too scary, but filling out forms on the Web is still a dicey business, a researcher said this week.

In an update of his 2002 paper, which exposed many of the vulnerabilities associated with HTML forms, EnableSecurity's Sandro Gauci states that most browsers still haven't completely fixed the problems associated with commonly used forms.

"Does it still work? The short answer is yes," Gauci says in the updated paper. "Most popular Web browsers seem to block certain well-known ports. However, there are many cases where an attacker can make use of ports which are not on the blacklist." And Internet Explorer and Opera don't block as many ports as Safari or Firefox, he says.

The problem, in part, is that most browsers do their best to render any data they receive in HTML, Gauci explains. While the browser vendors have generally shored up the vulnerabilities in Web forms that are exchanged with an HTML server, most of them have done little about the exchange of forms between a browser and a non-HTTP server, such as an FTP or SMTP server.

Since the browser has no way of distinguishing between an HTTP server and a non-HTTP server, a user might be enticed to browse to a non-HTTP server, which would typically send an error message to the browser, the paper says. But a wily hacker might be able to attach malicious code to the error message, and potentially launch a cross-site scripting (XSS) attack or steal data from the browser that would allow him to gain access to the user's information or take over the user's machine. .

"When an attacker can control what is returned by the server, the victim becomes vulnerable to security issues such as [XSS]," Gauci writes. "In the case of HTTP servers, this is a well-known issue, and therefore modern Web servers do not exhibit this behavior by default.

"However, this is not the case with other kinds of servers, such as SMTP or FTP servers, [which] often echo back error messages containing user input," the paper observes. "When this user input can be controlled by the attacker, bad things can happen."

To repair the vulnerability, browser vendors will need to re-tool their browsers so that they do not attempt to render responses from non-HTTP servers in HTML, Gauci says.

"One solution would be to check the HTTP response headers and make sure that they are indeed HTTP 1.0 or 1.1-compliant," he says. "This would identify IMAP or FTP servers responding with malicious HTML. When the HTTP response headers are not found, the Web browser should not render the content as HTML."

Have a comment on this story? Please click "Discuss" below. If you'd like to contact Dark Reading's editors directly, send us a message.

Tim Wilson is Editor in Chief and co-founder of Dark Reading.com, UBM Tech's online community for information security professionals. He is responsible for managing the site, assigning and editing content, and writing breaking news stories. Wilson has been recognized as one ... View Full Bio

Comment  | 
Print  | 
More Insights
Comments
Threaded  |  Newest First  |  Oldest First
Cloud Security Startup Lightspin Emerges From Stealth
Kelly Sheridan, Staff Editor, Dark Reading,  11/24/2020
Why Vulnerable Code Is Shipped Knowingly
Chris Eng, Chief Research Officer, Veracode,  11/30/2020
Look Beyond the 'Big 5' in Cyberattacks
Robert Lemos, Contributing Writer,  11/25/2020
Register for Dark Reading Newsletters
White Papers
Video
Cartoon Contest
Write a Caption, Win an Amazon Gift Card! Click Here
Latest Comment: I think the boss is bing watching '70s TV shows again!
Current Issue
2021 Top Enterprise IT Trends
We've identified the key trends that are poised to impact the IT landscape in 2021. Find out why they're important and how they will affect you today!
Flash Poll
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2020-28971
PUBLISHED: 2020-12-01
An issue was discovered on Western Digital My Cloud OS 5 devices before 5.06.115. A NAS Admin authentication bypass vulnerability could allow an unauthenticated user to execute privileged commands on the device via a cookie, because of insufficient validation of URI paths.
CVE-2020-28993
PUBLISHED: 2020-12-01
A Directory Traversal vulnerability exists in ATX miniCMTS200a Broadband Gateway through 2.0 and Pico CMTS through 2.0. Successful exploitation of this vulnerability would allow an unauthenticated attacker to retrieve administrator credentials by sending a malicious POST request.
CVE-2020-6880
PUBLISHED: 2020-12-01
A ZXELINK wireless controller has a SQL injection vulnerability. A remote attacker does not need to log in. By sending malicious SQL statements, because the device does not properly filter parameters, successful use can obtain management rights. This affects: ZXV10 W908 all versions before MIPS_A_10...
CVE-2020-28940
PUBLISHED: 2020-12-01
On Western Digital My Cloud OS 5 devices before 5.06.115, the NAS Admin dashboard has an authentication bypass vulnerability that could allow an unauthenticated user to execute privileged commands on the device.
CVE-2020-28970
PUBLISHED: 2020-12-01
An issue was discovered on Western Digital My Cloud OS 5 devices before 5.06.115. A NAS Admin authentication bypass vulnerability could allow an unauthenticated user to execute privileged commands on the device via a cookie. (In addition, an upload endpoint could then be used by an authenticated adm...