Adversaries may insert, delete, or manipulate data at rest in order to influence external outcomes or hide activity, thus threatening the integrity of the data.(Citation: FireEye APT38 Oct 2018)(Citation: DOJ Lazarus Sony 2018) By manipulating stored data, adversaries may attempt to affect a business process, organizational understanding, and decision making.

Stored data could include a variety of file formats, such as Office files, databases, stored emails, and custom file formats. The type of modification and the impact it will have depends on the type of data as well as the goals and objectives of the adversary. For complex systems, an adversary would likely need special expertise and possibly access to specialized software related to the system that would typically be gained through a prolonged information gathering campaign in order to have the desired impact.
Stored Data Manipulation
source_name: mitre-attack  url: https://attack.mitre.org/techniques/T1565/001  external_id: T1565.001     source_name: DOJ Lazarus Sony 2018  description: Department of Justice. (2018, September 6). Criminal Complaint - United States of America v. PARK JIN HYOK. Retrieved March 29, 2019.  url: https://www.justice.gov/opa/press-release/file/1092091/download     source_name: FireEye APT38 Oct 2018  description: FireEye. (2018, October 03). APT38: Un-usual Suspects. Retrieved November 6, 2018.  url: https://content.fireeye.com/apt/rpt-apt38     