# Malware Analysis

## Forensics CheatSheets

[https://www.jaiminton.com/cheatsheet/DFIR/\#](https://www.jaiminton.com/cheatsheet/DFIR/#)

## Online Services

* [VirusTotal](https://www.virustotal.com/gui/home/upload)
* [HybridAnalysis](https://www.hybrid-analysis.com)
* [Koodous](https://koodous.com/)
* [Intezer](https://analyze.intezer.com/)

## Offline antivirus

### Yara

#### Install

```bash
sudo apt-get install -y yara
```

#### Prepare rules

Use this script to download and merge all the yara malware rules from github: [https://gist.github.com/andreafortuna/29c6ea48adf3d45a979a78763cdc7ce9](https://gist.github.com/andreafortuna/29c6ea48adf3d45a979a78763cdc7ce9)  
Create the _**rules**_ directory and execute it. This will create a file called _**malware\_rules.yar**_ which contains all the yara rules for malware.

```bash
wget https://gist.githubusercontent.com/andreafortuna/29c6ea48adf3d45a979a78763cdc7ce9/raw/4ec711d37f1b428b63bed1f786b26a0654aa2f31/malware_yara_rules.py
mkdir rules
python malware_yara_rules.py
```

#### Scan

```bash
yara -w malware_rules.yar image  #Scan 1 file
yara -w malware_rules.yar folder #Scan hole fodler
```

#### YaraGen: Check for malware and Create rules

You can use the tool [**YaraGen**](https://github.com/Neo23x0/yarGen) to generate yara rules from a binary. Checkout these tutorials: [**Part 1**](https://www.nextron-systems.com/2015/02/16/write-simple-sound-yara-rules/), [**Part 2**](https://www.nextron-systems.com/2015/10/17/how-to-write-simple-but-sound-yara-rules-part-2/), [**Part 3**](https://www.nextron-systems.com/2016/04/15/how-to-write-simple-but-sound-yara-rules-part-3/)

```bash
 python3 yarGen.py --update
 python3.exe yarGen.py --excludegood -m  ../../mals/
```

### ClamAV

#### Install

```text
sudo apt-get install -y clamav
```

#### Scan

```bash
sudo freshclam      #Update rules
clamscan filepath   #Scan 1 file
clamscan folderpath #Scan the hole folder
```

### IOCs

IOC means Indicator Of Compromise. An IOC is a set of **conditions that identifies** some potentially unwanted software or a confirmed **malware**. Blue Teams use this kind of definitions to **search for this kind of malicious files** in their **systems** and **networks**.  
To share these definitions is very useful as when a malware is identified in a computer and an IOC for that malware is created, other Blue Teams can use it to identify the malware faster.

A tool to create or modify IOCs is ****[**IOC Editor**](https://www.fireeye.com/services/freeware/ioc-editor.html)**.**  
You can use tools such as ****[**Redline**](https://www.fireeye.com/services/freeware/redline.html) ****to search for IOCs in a device.

### rkhunter

Tools like [**rkhunter**](http://rkhunter.sourceforge.net/) can be used to check the filesystem for possible **rootkits** and malware.

```bash
sudo ./rkhunter --check -r / -l /tmp/rkhunter.log [--report-warnings-only] [--skip-keypress]
```

### PEpper

[PEpper ](https://github.com/Th3Hurrican3/PEpper)checks some basic stuff inside the executable \(binary data, entropy, URLs and IPs, some yara rules\).

### Apple Binary Signatures

When checking some **malware sample** you should always **check the signature** of the binary as the **developer** that signed it may be already **related** with **malware.**

```bash
#Get signer
codesign -vv -d /bin/ls 2>&1 | grep -E "Authority|TeamIdentifier"

#Check if the app’s contents have been modified
codesign --verify --verbose /Applications/Safari.app

#Check if the signature is valid
spctl --assess --verbose /Applications/Safari.app
```