APT-17 group aka BITTER APT group has been recently active and targeting sectors in South Asia for information theft and espionage. This group has a history of targeting Energy, Engineering, Government in South Asia. Spear phishing emails have been the main strike force to target their victims and they’ve been doing it for years now. Many BITTER victims have been exploited through relatively popular Microsoft Office exploit, in order to download and execute a RAT binary from a website. Although the attack vector of this sample remains unknown of yet, this is an indication of their presence again in the South Asian region. As part of an ongoing effort that began in August 2021, this threat actor group known for targeting China, Pakistan, and Saudi Arabia has expanded to set its sights on Bangladeshi government agencies.
With a spear-phishing email, this campaign targets an elite unit of Bangladesh’s government. Emails may contain a malicious RTF document or a Microsoft Excel spreadsheet that is used to exploit known vulnerabilities. The Equation Editor application is automatically launched once the victim opens the maldoc to run the embedded objects containing the shellcode to exploit known vulnerabilities described by CVE-2017-11882, CVE-2018-0798, and CVE-2018-0802 in Microsoft Office, and then downloads and runs the trojan from the hosting server on the victim’s machine. The trojan runs itself in this campaign, but the actor has more RATs and downloaders in their arsenal.
Researchers analyzed a recent attack carried out by this APT group. The campaign specifically targets Bangladeshi (military) groups. Threat actors use Remote Access Trojans to perform espionage using malicious document files and intermediary malware stages. Bitter uses malicious document files with “Equation Editor exploits” as baits to download further malware stages. The Loader in the second step collects information about the infected system. The third stage of a Bitter attack can include several sorts of Malware, such as keyloggers, stealers, or remote access Trojans (Almond RAT was also utilized)