I write this from practical experience hardened by too many midnight incident calls. Non-Approved Messaging Apps are a persistent gap in secure communications. They create easy backchannels that bypass controls, audit trails and record retention. The Signalgate episode is a clear example: senior staff shared operational details to a Signal group minutes before an action, and the incident exposed gaps in control and discipline [https://www.computerworld.com/article/4101885/insecure-use-of-signal-app-part-of-wider-department-of-defense-problem-suggests-senate-report-2.html].
Shadow IT starts small. Someone installs an app on a personal phone because it is quick and convenient. The Signal app offers end-to-end encryption and ease of use, so staff pick it for private conversations. That convenience comes at a cost. Encryption alone does not solve record-keeping or classification. If a message contains sensitive information it still needs to be preserved, classified and available for legal or operational review. A Senate committee noted personnel “used non-DoD-controlled electronic messaging systems for a variety of reasons” and that increased the risk of exposing sensitive information. Personal devices evade MDM controls and corporate logging. Unapproved apps can leak attachments, screenshots and metadata. They also create forensic blind spots during investigations.
Mitigation requires technical controls and operational rules that actually work in the field. Start by giving people a good alternative. Approve and deploy a supported messaging tool that meets your retention and e-discovery needs, and make it as simple to use as the consumer alternatives. Use mobile device management to enforce app allowlists, containerised mail and messaging, and to block sideloading. Apply data loss prevention rules to mobile endpoints so attachments and classified text are prevented from leaving controlled containers. At the network edge, block known non-approved messaging API endpoints where policy permits. Use conditional access so only compliant devices can access sensitive services. Limit authority to send classified operational details to a handful of authorised accounts and hard-code that into communication protocols. That reduces accidental disclosures like the Signalgate leak.
Training and rules must be surgical, not vague. Teach staff what must be recorded, where to save it and how long to keep it. Run short, realistic exercises that show how an informal message can become an evidential trail. Hold senior staff accountable with policy that ties messaging privileges to certification, not rank alone. Audit for shadow IT with periodic mobile sweeps, network telemetry and app inventory reports from MDM. Measure compliance with concrete metrics: percentage of devices enrolled in MDM, number of non-approved apps detected, and time to remediate a flagged device. Make retention policies auditable and integrate them with legal and records teams so classification and preservation are automatic.
Finally, accept trade-offs and set tolerances. No technical control is perfect. People will try workarounds if the authorised tool is clumsy. My approach is pragmatic: reduce friction for approved tools, make non-approved options harder to use in operational contexts, and design protocols that keep sensitive details off ad-hoc channels. That means clear communication protocols, enforced app allowlists, mandatory training and targeted audits. Do these, and we shrink the blind spots that shadow IT creates. The last result should be simple: fewer informal backchannels, auditable records, and faster, cleaner incident response.
