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Chrome 63 offers even more protection from malicious sites, using even more memory

7 Prosinec, 2017 - 22:50

Enlarge / You might need more of this stuff if you want to use Chrome's new Site Isolation mode. Well, not this stuff exactly; it's RAM from a very obsolete VAX computer. (credit: Kevin Stanchfield)

To further increase its enterprise appeal, Chrome 63—which hit the browser's stable release channel yesterday—includes a couple of new security enhancements aimed particularly at the corporate market.

The first of these is site isolation, an even stricter version of the multiple process model that Chrome has used since its introduction. Chrome uses multiple processes for several security and stability reasons. On the stability front, the model means that even if a single tab crashes, other tabs (and the browser itself) are unaffected. On the security front, the use of multiple processes makes it much harder for malicious code from one site to steal secrets (such as passwords typed into forms) of another.

Chrome's default model is, approximately, to use one process per tab. This more or less ensures that unrelated sites are kept in separate processes, but there are nuances to this set-up. Pages share a process if they are related through, for example, one opening another with JavaScript or iframes embedding (wherein one page is included as content within another page). Over the course of a single browsing session, one tab may be used to visit multiple different domains; they'll all potentially be opened within a single process. On top of this, if there are already too many Chrome processes running, Chrome will start opening new pages within existing processes, resulting in even unrelated pages sharing a process.

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Kategorie: Hacking & Security

How to fix a program without the source code? Patch the binary directly

17 Listopad, 2017 - 22:24

Enlarge (credit: Flickr user: Ivan T)

When a company like Microsoft needs to fix a security flaw in one of its products, the process is normally straightforward: determine where the bug lies, change the program's source code to fix the bug, and then recompile the program. But it looks like the company had to step outside this typical process for one of the flaws it patched this Tuesday. Instead of fixing the source code, it appears that the company's developers made a series of careful changes directly to the buggy program's executable file.

Bug CVE-2017-11882 is a buffer overflow in the ancient Equation Editor that comes with Office. The Equation Editor allocates a fixed-size piece of memory to hold a font name and then copies the font name from the equation file into this piece of memory. It doesn't, however, check to ensure that the font name will fit into this piece of memory. When provided with a font name that's too long, the Equation Editor overflows the buffer, corrupting its own memory, and an attacker can use this to execute arbitrary malicious code.

Curious how a buffer overflow works? Previously on Ars we did a deep-dive explanation. (video link)

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Kategorie: Hacking & Security

Firefox’s faster, slicker, slimmer Quantum edition now out

14 Listopad, 2017 - 15:00

Firefox is fast now. (credit: Mozilla)

Mozilla is working on a major overhaul of its Firefox browser, and, with the general release of Firefox 57 today, has reached a major milestone. The version of the browser coming out today has a sleek new interface and, under the hood, major performance enhancements, with Mozilla claiming that it's as much as twice as fast as it was a year ago. Not only should it be faster to load and render pages, but its user interface should remain quick and responsive even under heavy load with hundreds of tabs.

Collectively, the performance work being done to modernize Firefox is called Project Quantum. We took a closer look at Quantum back when Firefox 57 hit the developer channel in September, but the short version is, Mozilla is rebuilding core parts of the browser, such as how it handles CSS stylesheets, how it draws pages on-screen, and how it uses the GPU.

This work is being motivated by a few things. First, the Web has changed since many parts of Firefox were initially designed and developed; pages are more dynamic in structure and applications are richer and more graphically intensive. JavaScript is also more complex and difficult to debug. Second, computers now have many cores and simultaneous threads, giving them much greater scope to work in parallel. And security remains a pressing concern, prompting the use of new techniques to protect against exploitation. Some of the rebuilt portions are even using Mozilla's new Rust programming language, which is designed to offer improved security compared to C++.

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Kategorie: Hacking & Security