In the web application world – especially single-page applications – smooth and fluid interaction is key. For many years, these applications have been doing a pretty good job of getting this fluid interaction though AJAX techniques and browser support for XMLHttpRequest. One issue, however, is that XMLHttpRequest requires that all of your communication go through an text-based HTTP protocol. Another issue …
Read moreIn 2003, Crosby and Wallach wrote an excellent paper demonstrating a new form of Denial of Service vulnerability against applications by abusing algorithmic complexity in the data structures that they depend on. For example, some data structures operate quite efficiently when given everyday input, but the performance degrades precipitously in certain edge cases.
If an application provides user-controlled data to one …
Read moreAfter posting Extracting Activity History from PowerShell Process Dumps, I got an interesting follow up question: “Is it possible to extract the content of scripts (from disk) that were executed, even if those files were not captured?”
The answer is “Yes”, but it’s also complicated. And to make it even more complicated, we’re going to go down a path showing how to do some of this detective work from scratch. This is …
Read moreImagine that you’re investigating the compromise of a system. The system doesn’t have PowerShell Logging enabled, but you did capture a process dump while activity was happening.
This memory dump is forensic gold, and the managed code debugging extension for WinDbg (“SOS” – Son of Strike) gives you all the tools you need to mine it. After using File | Open Crash Dump, this is what you see:
From there, load the SOS …
Read moreAfter it’s done indexing your data, Scour is blazingly fast at local content searches – far faster than Select-String, grep, or anything else that rips through files when you search. It accomplishes this through the power of the popular Lucene search engine. Similar to the way that publishers have made searching physical books fast, Lucene must first create an index of your content before you can search it.
So while …
Read moreIf you have a large collection of documents (source code or text files), searching them with PowerShell or your favourite code editor can feel like it takes forever.
How is it that we can search the entire content of the Internet in milliseconds, but searching your local files can take minutes or hours?
It turns out that there is a solution built into many products and technologies that can help us: the Apache Lucene …
Read moreSo you’re interested in submitting a talk for a security conference? Awesome! Above all else, what keeps our industry moving forward is the free and open sharing of information. Submitting a talk can be a scary experience, and the process for how talks are evaluated can feel mysterious.
So what’s the best way to create a good security conference CFP submission?
It’s perhaps best to consider the questions that the …
Read moreMandiant recently posted some research about an attack leveraging the NetSupport Remote Access tool. The first stage of this attack uses a lot of obfuscation tricks to try to make reverse engineering more difficult.
David Ledbetter and I were chatting about some of the lengths the malware authors went through to obfuscate the content.
One of the major sources of complication is a complicated, iterative XOR:
(Image …
Read moreWhen analyzing text, a common goal is to identify the parts of speech within that text – what parts are nouns? Adjectives? Verbs in their gerund form?
To accomplish this goal, the area of natural language processing in Computer Science has developed systems for Part of Speech tagging, or “POS Tagging”. The acronym preceded the version in Urban Dictionary :)
The version I used in University was a Perl-based Brill …
Read moreK-Means clustering is a popular technique to find clusters of data based only on the data itself. This is most commonly applied to data that you can somehow describe as a series of numbers.
When you can describe the data points as a series of numbers, K-Means clustering (Lloyd’s Algorithm) takes the following steps:
