The technique exploits Netskope's default recursion depth limitation in content inspection, which is less than three levels. Sensitive data (secret.txt) is zipped, appended to a PNG image using Windows CMD's binary copy command, and then embedded into a PPTX file. Netskope inspects the PPTX as a ZIP and finds the PNG image but does not recurse into the appended ZIP inside the PNG, allowing data exfiltration without detection. The appended ZIP is a non-standard corrupt archive that native Windows tools cannot extract, requiring forensic tools like binwalk for extraction. Metadata anomalies (.txtux and .ux extensions) appear in the PNG metadata and can be used for detection without increasing recursion depth. Mitigations include increasing Netskope's recursion depth, creating metadata anomaly DLP rules, and deploying SentinelOne behavioral rules to alert on suspicious CMD binary concatenation commands. Combining SentinelOne endpoint alerts with Netskope network inspection creates a coordinated detection strategy.

Sensitive data such as PII, credentials, or internal documents can be exfiltrated from managed corporate endpoints without triggering Netskope DLP alerts under default configurations. The technique requires no additional software installation or admin rights on the source machine and works across all Microsoft Office file formats that use ZIP-based structures. This bypass could lead to undetected data leakage through standard channels like email or web uploads.

Mitigations have been proposed and documented by the researcher and reported internally. Recommended actions include: 1) Increasing Netskope's inspection recursion depth beyond three levels to detect deeply nested files, acknowledging potential performance impacts; 2) Implementing Netskope DLP rules targeting anomalous metadata extensions (.txtux, .ux) to detect this technique without deeper recursion; 3) Deploying SentinelOne EDR behavioral rules to alert on CMD commands performing binary file concatenation (copy /b), enabling endpoint detection of steganographic file preparation; 4) Correlating SentinelOne alerts with Netskope network inspection to create a coordinated detection and response workflow. Blocking cmd.exe is not advised due to legitimate operational use; monitoring and alerting is preferred. Patch status is not applicable as this is a detection and configuration issue rather than a software vulnerability.