Office (OOXML) / .XLSX malware analysis — malicious · 55d588dcef51165b

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: b5e8c2110c08927c2f3df9fb75fe9b32 SHA-1: eb78cad4a4d8b309f36c06dca5f60de121ff8207 SHA-256: 55d588dcef51165ba11f2cd72ce3a93b2409046218a3e8ba7d9740a9105ff667

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 extracted macro content, though truncated, shows a path string 'C:\ProgramData\excel.rtf' which is likely an attempt to write a malicious file to disk. This suggests the macro's primary function is to download and execute a secondary payload, a common technique for initial access.

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` `f5c2ca8081d686acd6ce3169a0c736b341db330e53727b8d6618adeda104e9fd`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	260772 bytes

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