Hackers use weaponized Word documents to deliver malicious payloads through social engineering.
By embedding malware or exploiting vulnerabilities in these documents, attackers trick users into opening them and leading to the execution of malicious code.
While leveraging the familiarity and trust associated with such file format, this tactic is effective for several illicit purposes:-.
Recently, cybersecurity researchers at Netskope identified a new Nim-based malware, which was delivered via weaponized Word documents by the threat actors.
Nim is a new language that sees a rising malware trend, and experts at Netskope Threat Labs note growing Nim-based threats, anticipating further popularity.
The malicious Word doc drops the Nim backdoor, which is sent as an email attachment by a fake Nepali official.
Despite macro security, APT malware, like Menorah, which used a similar tactic months ago, still leverages macros for payload delivery.
Opening the file shows a blank doc, prompts macro to enable, and then the clicking triggers the:-.
VBA project uses passwords and obfuscation to dodge AV solutions.
At the same time, the macros employ Chr( ) and string concatenation.
Apart from this, the code is divided into four subroutines, and here below we have mentioned them:-.
Nim is a versatile language that compiles the following languages together with Pythonic syntax:-.
Backdoor operates with user's privileges, mimicking Nepali authority to deceive users.
Nim backdoor checks for analysis tools and terminates if found.
It fetches the hostname and encrypts it with the 'bakery' function.
The encrypted hostname double-base64 encoded, which was:-.
The C&C server issues the commands via HTTP GET, the response is decrypted by the 'confectionary' function, executed with cmd /c, and then the result is sent back to the server.
Here below, we have mentioned all the C2 hosts that were contacted:-.
On success, it runs '8lGghf8kIPIuu3cM.bat,' and the batch file drops the files and creates tasks for payload. Meanwhile, the 'd.bat' establishes the persistent execution with the scheduled task 'ConsoleHostManager.
Malware in rare languages challenges security experts, and the cross-compilation in Nim aids hackers in creating obstacles for security analysts.
This Cyber News was published on gbhackers.com. Publication date: Wed, 27 Dec 2023 15:13:07 +0000