Office (OOXML) / .XLSX malware analysis — malicious · c9f015fdfab1f1f0

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 922fa1065b6ef2e01960943aac476afb SHA-1: 107830b1fc48560e7075aada6d69d6bb925d25c8 SHA-256: c9f015fdfab1f1f063eb722db4588d8297ea94f47231d3d802c4a148324c5d6e

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an Excel file containing Excel 4.0 macros, as indicated by the OOXML_XLM_MACROSHEET heuristic. The macro code appears to be attempting to execute a command that involves a path, likely for downloading and running a secondary payload. The reconstructed path "C:\ProgramData\fnsfunsgfgrgnkjfsgnd" is suspicious and warrants investigation.

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` `bcd5db32915d74cb76a38e869d407517f471d6da29241e66d2eb0c06789540a0`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	3726 bytes

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