Office (OOXML) / .XLSX malware analysis — malicious · 8dc96849737a44eb

MALICIOUS

Office (OOXML) / .XLSX

191.0 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2021-10-31

MD5: 9f13a62b3e30b90fc926f6ebc63ccab9 SHA-1: f4f49a535c113ae5c2958448a445a3f6a8d57083 SHA-256: 8dc96849737a44eb8b37f0f5012764f66f3b713be548671d4b7b2900b05e2237

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an Excel file containing Excel 4.0 macros. The macros appear to be constructing a file path, 'C:\ProgramData\excel.rtf', likely for downloading and executing a second-stage payload. The specific intent of the macro is to write this path to disk, which is a common technique for staging malware.

Heuristics 1

Excel 4.0 macro sheet (1 sheet(s)) critical OOXML_XLM_MACROSHEET

Spreadsheet contains an Excel 4.0 (XLM) macro sheet — XLM was a major Office malware vector during 2020-2022 and evaded many VBA-focused controls before Microsoft tightened XLM defaults. Even legitimate XLM use is rare in modern workbooks. The macro sheet is stored as XLSB/BIFF12 binary content, which many XML-only OOXML scanners miss.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.bin` `38428da48a0b30e5248eff47cebb4fc769870f7975884f0dee14c617b87f1bec`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	433165 bytes

Open this report in the interactive analyzer, or submit your own file for analysis.