Office (OOXML) / .XLSX malware analysis — malicious · 85dc1d55b4832a66

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 5d100282fa245a22e4d7fd4d3756dc73 SHA-1: e616e28b6c93b59f48bd119ed1d722794b95fd8d SHA-256: 85dc1d55b4832a6669a8de1a1d69151f26a63a3ed8a0568a77d89aad31f57712

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file is an Excel spreadsheet containing Excel 4.0 macros, which are known to be used for malicious purposes. The heuristic firing indicates the presence of these macros, suggesting an attempt to execute arbitrary commands. The macros are likely used to download and execute a secondary payload, a common technique for malware delivery.

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` `4120bf0ae47c1939fd362d58c579becf0b8ba94d067c100ae5523c4bcc8067a4`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	7124 bytes

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