Adversaries may exfiltrate data to a code repository rather than over their primary command and control channel. Code repositories are often accessible via an API (ex: https://api.github.com). Access to these APIs are often over HTTPS, which gives the adversary an additional level of protection. Exfiltration to a code repository can also provide a significant amount of cover to the adversary if it is a popular service already used by hosts within the network.
Office or scripting applications initiating unusual HTTPS traffic to code repository APIs with high outbound-to-inbound ratios. Defender perspective: monitor for sensitive file access in combination with network connections to github.com, gitlab.com, or bitbucket.org.
Processes such as PowerShell, Git, or curl initiating outbound HTTPS POST requests to known code repository APIs (e.g., github.com, gitlab.com) immediately following large file reads. Defender view: correlation between file access of sensitive directories (e.g., Documents, Finance) and abnormal data uploads to repository domains.
Processes like git, curl, or python scripts executing commands that package files (tar, gzip) followed by HTTPS uploads to code repository endpoints. Defender view: detect unusual git push activity or scripted HTTPS requests outside normal developer work hours.