A surge of malspam campaigns has been recently attributed to Emotet botnet. Taking advantage of password-protected archive files, the notorious trojan drops CoinMiner and Quasar RAT on the systems it takes over.
In an attack chain detected by Trustwave SpiderLabs researchers, an invoice-themed ZIP file lure was found to contain a nested self-extracting (SFX) archive, with the first archive having the purpose to launch the second.
Emotet is known to primarily spread through malspam and, while phishing attacks usually rely on persuasion techniques in order to trick the victims into opening the attachment, this time researchers claim the campaign bypassed this by making use of a batch file to automatically supply the password to unlock the payload. The first archive is a RARsfx, only meant to execute a second RARsfx contained within itself. The second archive is password-protected but no user input is necessary to extract and execute its content.
The self-extracting archive has been around for a long time and eases file distribution among end users. However, it poses a security risk since the file contents are not easily verifiable, and it can run commands and executables silently.Source
Once inside, the infection proceeds with the execution of CoinMiner, a cryptocurrency miner that can also double up as a credential stealer, or Quasar RAT, an open-source remote access trojan, depending on the payload packed in the archive.
This attack technique enables threat actors to bypass the password barrier, making it easier for them to carry out attacks such as cryptojacking, data exfiltration, and even ransomware.
Trustwave researchers claim there has been a noticeable increase in threats packaged in password-protected archives, 96% of them being spammed by the Emotet botnet.
Stay informed of the latest Cybersecurity trends, threats and developments. Sign up for our Weekly Cybersecurity Newsletter Today.
Remember, CyberSecurity Starts With You!
- Globally, 30,000 websites are hacked daily.
- 64% of companies worldwide have experienced at least one form of a cyber attack.
- There were 20M breached records in March 2021.
- In 2020, ransomware cases grew by 150%.
- Email is responsible for around 94% of all malware.
- Every 39 seconds, there is a new attack somewhere on the web.
- An average of around 24,000 malicious mobile apps are blocked daily on the internet.