Showing posts with label dtrack. Show all posts
Showing posts with label dtrack. Show all posts

Thursday, February 18, 2021

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When you go fighting malware don´t forget your VT plugins

It's been a year since we launched our VirusTotal plugin for IDA Pro, followed by SentinelOne’s amazing contribution to the community with their VirusTotal plugin for GHIDRA (thanks again for the great job), inspired by the original IDA plugin but adding some cool extra features.

Now, what are IDA Pro and Ghidra? These tools are the more popular disassemblers used by the security community for malware analysis. Basically, they help researchers to understand the functionality of the code used to build the malware.

Most of VirusTotal’s users simply use the web interface or the API in order to do their investigations or enrich their threat intelligence systems, so how and when do these plugins come handy?

Before we go on, make sure to join us for our next webinar with SentinelOne next February 24th where we will demonstrate how to use both plugins with real life examples. Join us and register here!

Looking inside the malware

VirusTotal usually provides all we need to know about a malware sample and more, especially when it comes to context and the relationships with other samples or malicious infrastructure. However, sometimes as analysts we need to take a deeper look, here is when we IDA Pro and Ghidra come to the rescue.

What do VirusTotal's plugins for these disassemblers have to offer? Basically, they make analysts’ life easier by providing several handy functionalities that leverage VirusTotal’s knowledge base. For instance, in one click we can search for samples that use a specific relevant piece of code that we found in the sample we are analyzing. Indeed, plugins’ code similarity search functionality offers new ways to find related samples that aren't easily reachable without going down into the reversing process.

We will usually want to find samples with a similar set of instructions than the one we are analyzing. Let's see an example. If we take a look at both WinMain functions of two different samples (as shown below) it is clear that they are practically identical, only differing in the value of some operands.



If we omit these differences, we can see that they have the same structure and share the same set of instructions.




You never know what kind of valuable information you will find when analyzing a sample. It could be a very peculiar implementation, or a distinctive function that attackers implement in all their samples. It also could be that we are taking a look into earlier versions of recently deployed malware, giving us the opportunity to understand its evolution before attackers implement anti-reversing techniques.

Analyzing corrupted files

Code similarity provides additional advantages. Let’s consider the case where we have some corrupted samples of a recent malware strain. They can be just memory dumped files, or PE files that were modified during the execution - anyways we cannot execute them. These kinds of files are not the best for creating YARA rules, because there is a chance that the content has been modified before the memory image was dumped to disk. In these scenarios is where the use of VirusTotal plugins shine, as we can search for code that we find interesting enough for finding related samples. We previously described this technique to hunt Ryuk samples starting from a corrupted one.

There are many other ways in which these plugins can assist you for code analysis. For instance, we can look for code similarity during a debugging session, the advantage being we can search for decrypted or uncompressed samples uploaded to VirusTotal by just searching for some instructions obtained in runtime. We'll further explore this technique in our webinar with SentinelOne.

What’s next?

So what is the future of the VirusTotal's plugin for IDA Pro? We are working hard on implementing a new exciting set of features focused on assisting you during the reversing process. For instance, we plan to collect contextual information from our database about the sample you are working in and show it in the IDA interface. We will also enrich the disassembled code to highlight the most significant information collected from VirusTotal.

We will show you more about what will be in the new version in our joint webinar next February 24th!

See you there and Happy hunting!

This post was co-authored by Vicente Diaz.

Monday, February 10, 2020

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Official VirusTotal Plugin for IDA Pro 7

ATTENTION: In order to use the content search functionality you will need to have access to VT Intelligence. If you want to jump straight ahead and install the plugin, please refer to its GitHub repository.





VirusTotal is very excited to announce a beta release of a new plugin for IDA Pro v7 which integrates VT Intelligence’s content search directly into IDA.

This plugin adds a new "VirusTotal" entry to the IDA Pro context menu (disassembly and strings windows), enabling you to search for similar or exact data on VirusTotal. It translates the user selection into a query that VTGrep understands.

The current beta release provides the following search options:
  • Search for bytes: it searches for the bytes contained in the selected area.
  • Search for string: it searches for the same string as the one selected in the Strings Window.
  • Search for similar code: identifies memory offsets or addresses in the currently selected area and ignores them when searching.
  • Search for similar code (strict): same as above but it also ignores all the constants in the currently selected area.
  • Search for similar functions: same as "similar code" but you don’t need to select all the instructions that belong to a function. Just right-click on one instruction, and it will automatically detect the function boundaries, selecting all the instructions of the current function.



Using VTGrep content search to trace DTrack samples


As an example of how this plugin can speed up the analysis process, we have conducted a preliminary analysis of the DTrack sample that appeared last October 2019. As a reminder, this malware was used in an attack against the Kudankulam Nuclear Power Plant (KKNPP - India) on September 4, 2019, but was not publicly acknowledged by India’s Nuclear Power Corporation of India Limited (NPCIL) until nearly the end of October.

It's not the first time that a DTrack sample reuses code from previous attacks. Indeed, if we search for the string dkwero38oerA^t@# (VT Intelligence query: content:"dkwero38oerA^t@#") we can find 79 samples in VirusTotal that contain this string, and some of them are DTrack samples.



This string is used as a key to compress a "C.TMP" file containing files and directories of "C:\" (one zip file per connected device). There's another interesting string (abcd@123) that's used to encrypt a zip file containing all the evidence collected. There are a total of nine occurrences of this second string in the VirusTotal database.

These results can serve as a starting point to dive into previous versions of this sample. Additionally, we can look for similar code in the VirusTotal database. If we select the WinMain function's code, one sample shows up that looks promising.



Comparing both WinMain functions, we can see that they are almost identical; they only differ in the values of memory addresses and offsets. Therefore, we can argue that we've just found another version of the current sample because this match points to another file that starts with the same code.


Thus, just one click ahead of the WinMain function, we are driven to another sample that looks interesting.

There’s another approach we can take to find related samples. We can search for identical sequences of strings. Although generated code usually changes between compilations, strings are placed in the same order inside the file. Taking a look at the strings used for gathering information about the current IP addresses, running processes, and open ports, we can jump to another sample that looks similar.



We’ve just landed on another sample that shares code with our DTrack file. Taking a look at the disassembly, we can see a lot of similar functions (401B10, 402EB0, 4020E0, 403730, etc.). Even the function located at 11933B0 (related to the last search) seems to be a more completed version of the function located at 4038B0 in this last sample ("sct.jpg").

Keep in mind that the number of samples shown depends on your license type. Standard licenses allow 90 days retrospection, but Threat Hunter PRO will allow you to go back in time one year.

As we continue to develop this plugin here is some additional functionality that we are considering for future releases:
  • Display a preview of the detection results in an IDA Pro window.
  • Automatically identify domains, IPs and URLs contained in the strings of the file and summarize their detection information.
  • Automatically suggest a YARA rule to detect the file.
  • VT Enterprise shortcuts, such as searching for similar files.
  • Automatically rank strings according to interest.
  • Annotations community and collaborative RE.
  • Improve the searching for similar functions (fuzzy hashes).
  • Enrich the disassembly with behavior information obtained from our sandboxes.

VirusTotal is interested in user feedback and priorities. Please do not hesitate to contact us to rank these features and suggest additional ones.