Description

In November 2023, a South Asian media organization was targeted using a newly discovered Go-based backdoor called GoGra, according to a report by Symantec. GoGra leverages the Microsoft Graph API for communication with a command-and-control (C&C) server hosted on Microsoft mail services. While the exact delivery method is unknown, GoGra is configured to read encrypted messages from an Outlook user named "FNU LNU" with the subject line beginning with "Input." Once decrypted using AES-256 in Cipher Block Chaining (CBC) mode, the backdoor executes commands via cmd.exe, encrypts the results, and sends them back to the same user under the subject "Output." GoGra is believed to be the work of the Harvester nation-state hacking group, noted for its use of similar tools like the NET-based Graphon, which also utilizes the Graph API for C&C. The incident is part of a broader trend of threat actors increasingly exploiting legitimate cloud services to evade detection. Other recent malware using this technique includes a data exfiltration tool by Firefly targeting a military organization in Southeast Asia, the Grager backdoor used in attacks across Taiwan, Hong Kong, and Vietnam, and MoonTag, attributed to a Chinese-speaking threat actor. Additionally, Onedrivetools has targeted IT services in the U.S. and Europe using OneDrive for C&C. Symantec notes that the rise in cloud-based C&C methods highlights a growing trend among espionage actors to mimic successful techniques from other groups.