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. 
Exfiltration to Code Repository
source_name: mitre-attack  url: https://attack.mitre.org/techniques/T1567/001  external_id: T1567.001     