Office (OOXML) / .XLSX malware analysis — malicious · c913b2e6ceba6bf3

MALICIOUS

Office (OOXML) / .XLSX

218.0 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000

MD5: a704ba444667afaefdcd0bd31208efbe SHA-1: bc17e020a0e256737761f20110df4159e2e0dd9b SHA-256: c913b2e6ceba6bf3d247c30451a82b1b8ebdba204b25eb410fd5d493dd0603b6

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristic firing indicates the presence of Excel 4.0 macros within the XLSX file. The macro sheet contains strings that appear to construct a file path, 'C:\ProgramData\excel.rtf', which is likely the intended location for a dropped payload or a temporary file used in the execution chain. The macro's purpose is to execute commands, making it a downloader or initial execution stage.

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` `0a7e7edabcd1f75ecaacb92d608573d4e6b382fb2a7c59522c38cc6e9d12dbff`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	565494 bytes

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