I am currently comparing different virtualization solutions for my home. This is because I want to do all kinds of things like openhab, cronjobs, DNS-based adblocking, and gateways both in via SSH and out via different VPNs/Tor, and splitting those into different machines sounds not only reasonable but is also necessary in some cases when there are different operating systems involved. This blag post will document a few nuggets of knowledge I collected while trying out VMware as hypervisor.
You want to know more?
The Zlob malware contains lots of bogus API calls to hinder analysis. This blag post describes how to use a script in Ghidra to automate the process of patching out those calls with
NOP instructions.
Is that even hard?!
Sometimes it really surprises me how something as mundane as JSON encoding and decoding
datetime objects in Python is not readily solve-able with a simple google query. I guess this is caused by the sheer amount of code fragments floating around confusing The Kraken. With this blag post, I'd happily like to add to this mess:
Show me your code snippet!
Since I already ran into this problem twice, here is a tiny reminder for my future self and potentially others that google something along the lines of the title. If you did
docker pull arangodb at some point in the past, then ran a ArangoDB container for a while with something like the command blow and want to update, just follow the error messages!
Follow them already!
Directing your attention as a reverse engineer is key for not wasting your life looking at irrelevant code. This blag post will use an anti-analysis technique used in the Zloader malware as an example to practice this art. We will also take a short detour into code-level obfuscation and are going to re-implement the API hashing function from Zloader in Python.
This post is aimed towards reverse engineering beginners that have already heard about API hashing. If you don't know, what Ghidra is or how to use it, you will need to brush over some parts of this post.
Tell me everything!
In this blog post, we will follow one of herrcore's awesome videos and re-implement the automation as a Ghidra script in Java. The video in question is part of a series about a legacy malware family called Hamweq. CERT Polska published an extensive analysis of Hamweq: The malware implements a IRC-based botnet with worm-like capabilities. In this post we will solely focus on the string deobfuscation functionality in the malware.
Show me what you got!
This blag post describes my though-process during identification of the string deobfuscation method in a sample belonging to the Zloader malware family. Specifically, I wanted to identify the function or functions responsible for string deobfuscation only using static analysis and Ghidra, understand the algorithm, emulate it in Java and implement a Ghidra script to deobfuscate all strings in a binary of this family.
The target audience of this post are people that have some experience with static reverse engineering and Ghidra but who always asked themselves how the f those reversing wizards identify specific functionality within a binary without wasting hours, days and weeks.
Show me what you got!
This post will explain, how to identify a function responsible for string deobfuscation in a native-PE malware sample. We will use a KpotStealer sample as a concrete example. KpotStealer (aka Khalesi or just Kpot) is a commodity malware family probably circulated in the shadowy parts of the internet since 2018. It got its name from a string publicly present on the Admin-Panel.
After we found the function we will understand the data structure it uses and emulate the decryption of a string with CyberChef and Binary Refinery. An interesting detail here is that Ghidra currently does not guess the function signature correctly.
Finally, we will develop a Java script (hehe) for Ghidra to automatically deobfuscate all strings given the corresponding obfuscation function.
Show me what you got!
There are two central problems that I faced with Slack:
1. Slack feels like I am developing in Eclipse, in a Windows VM, on an old Linux laptop. Where does all the bloat come from? It can't even have more than one channel open at a time!
2. In some cases, Slack can [force you to log out][SlackTimeout] after 12 hours, say. I understand why you would check that box as an IT admin, but I will show you that Slack is currently not enforcing this policy, and so I'd prefer to not be subject to it. 😼
## Good Slack Clients
The first problem is rather easy to solve, you simply use an alternative client. There are three options I am aware of:
- Using [WeeChat][] with the [WeeSlack][] plugin. I also recommend the [WeeEdit][] plugin to post multi line messages, especially for those code blocks. Finally, I use [WeeAutosort][] because the list of slack channels in WeeChat is a little confusing otherwise. This client is certainly your best option if your top priority is to go open source, to get it for free, or to use it on the command line. And it is a really good way to use Slack, too. I like it very much.
- You can use [Pidgin][] with the [slack-libpurple][SlackLibPurple] plugin. Unfortunately, I have to say that this works rather poorly and I mention it here only to be complete. I thoroughly recommend WeeChat if you are absolutely not willing to use a commercial and closed source program; it is better to use WeeChat with [WeeSlack][] in a terminal for Slack than to use the Pidgin plugin.
- If you are willing to pay $20 for your happiness, you should buy [Ripcord][] (Win/Linux/Mac supported). Even though it is in Alpha, it is the best Slack (and Discord!) client I have used. It supports Slack features in a more natural way because it is built specifically to do so, where in WeeChat some things may be awkward (inline images, navigating threads, etc). It is fast, has a low memory footprint, feels snappy, and gives you tabs for channels, DM's and threads. It is my weapon of choice.
[AndroidEmulator]: https://developer.android.com/studio/run/emulator
[AndroidEmulatorNetworking]: https://developer.android.com/studio/run/emulator-networking
[Ripcord]: https://cancel.fm/ripcord/
[MITMProxy]: https://mitmproxy.org/
[Pidgin]: https://pidgin.im/
[HAR]: https://en.wikipedia.org/wiki/HAR_(file_format)
[SlackLibPurple]: https://github.com/dylex/slack-libpurple
[WeeChat]: https://weechat.org/
[WeeSlack]: https://github.com/wee-slack/wee-slack
[WeeSlackSecure]: https://github.com/wee-slack/wee-slack#4-add-your-slack-api-keys
[SlackTimeout]: https://slack.com/intl/en-de/help/articles/115005223763-Manage-session-duration-?eu_nc=1
[SlackAPI]: https://api.slack.com/web
[SlackOverflow]: https://stackoverflow.com/questions/11012976/how-do-i-get-the-apk-of-an-installed-app-without-root-access
[NougatChanges]: https://android-developers.googleblog.com/2016/07/changes-to-trusted-certificate.html
[WeeEdit]: https://raw.githubusercontent.com/keith/edit-weechat/master/edit.py
[WeeAutosort]: https://raw.githubusercontent.com/de-vri-es/weechat-autosort/master/autosort.py
[WeeOTR]: https://raw.githubusercontent.com/mmb/weechat-otr/master/weechat_otr.py
## Loot Slack Tokens from Mobile
Now if you want to come along and get around periodic logouts in Slack with me, we'll have a bit of work to do.
This post describes the memory layout as well as the method used by the Sodinokibi (or REvil) ransomware to protect its strings. It will then list a few Java snippets to interact with the Ghidra scripting API and finally explain a working script to deobfuscate all strings within a REvil sample. If you don't care about the explaination, you can find the most recent version of the script you can simply import into Ghidra on github.
I want it all.
Since the temperature of scripting in Ghidra is so high at the current point in time, I want to tell you that scripting it in Java is so much better than scripting it in Python. After that I'll randomly motivate why one wants to get the "original bytes" from a sample and how to do it.
Show me what you got!
Found another rabbit hole! While reading my daily digest of tubes [an article about the Mozi bot](https://blog.netlab.360.com/mozi-another-botnet-using-dht/) sparked my interest. Peer-to-peer (P2P) botnets are always cool and this one has some worm-like capabilities and seems to hide its traffic within bittorrent communications. Naturally I wanted to take a look at the sample.
But you will not believe, what happened next!