An adversary may compress and/or encrypt data that is collected prior to exfiltration. Compressing the data can help to obfuscate the collected data and minimize the amount of data sent over the network.(Citation: DOJ GRU Indictment Jul 2018) Encryption can be used to hide information that is being exfiltrated from detection or make exfiltration less conspicuous upon inspection by a defender. Both compression and encryption are done prior to exfiltration, and can be performed using a utility, 3rd party library, or custom method.
Detects use of macOS-native archiving or encryption tools (zip, ditto, hdiutil) for staging collected data. Identifies unexpected invocation of archive utilities by Office apps, browsers, or background daemons. Correlates file creation of .zip/.dmg containers with process lineage anomalies.
Detects adversarial archiving activity through invocation of utilities like tar, gzip, bzip2, or openssl used in non-administrative or unusual contexts. Correlates command execution patterns with file creation of compressed/encrypted outputs in staging directories (e.g., /tmp, /var/tmp).
Detects adversarial archiving of files prior to exfiltration by correlating execution of compression/encryption utilities (e.g., makecab.exe, rar.exe, 7z.exe, powershell Compress-Archive) with subsequent creation of large compressed or encrypted files. Identifies abnormal process lineage involving crypt32.dll usage, command-line arguments invoking compression switches, and file write operations to temporary or staging directories.