Office (OOXML) / .XLSX malware analysis — malicious · 9823a04018133bb1

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: a9fd67c289294737cbf32409e7a7f976 SHA-1: 8b252ce4504332f0c216f9bd22975dee0a5a5cda SHA-256: 9823a04018133bb1c63862f26386a815c23b91ca745a0118af6d6f55a8805b96

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Service Execution: Service Control T1204.002 Malicious File: Malicious File

The sample is an Excel file containing Excel 4.0 macros. The macro executes a WMIC command to create a file named 'excel.rtf' in the 'C:\ProgramData\' directory and then attempts to launch it. This indicates a likely downloader or initial execution stage for further malicious activity.

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` `b775ec5b37cfb6a2ca99f20d6f43bc2a29b6f493c704b960e0f6923a67b96501`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	157217 bytes

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