Binary Padding
Where this stands
One published detection covers this technique. Every one is unverified — no rule on Siemphony has been executed against real telemetry.
What the technique is
Adversaries may use binary padding to add junk data and change the on-disk representation of malware. This can be done without affecting the functionality or behavior of a binary, but can increase the size of the binary beyond what some security tools are capable of handling due to file size limitations. Binary padding effectively changes the checksum of the file and can also be used to avoid hash-based blocklists and static anti-virus signatures. The padding used is commonly generated by a function to create junk data and then appended to the end or applied to sections of malware. Increasing the file size may decrease the effectiveness of certain tools and detection capabilities that are not designed or configured to scan large files. This may also reduce the likelihood of being collected for analysis. Public file scanning services, such as VirusTotal, limits the maximum size of an uploaded file to be analyzed.
Read it on attack.mitre.orgWhat MITRE says you would watch
- AN1528
Detects the creation or execution of padded binary files (e.g., large size but minimal legitimate content) followed by process execution or lateral movement from the host.
- AN1529
Detects abnormal creation of binary files with significant size that are subsequently executed or accessed by non-standard users.
- AN1530
Monitors for anomalous binary files written to disk with padded size and subsequent execution by user or service context.
Technique names and descriptions © MITRE ATT&CK®, CC BY 4.0. Not endorsed by MITRE.