Office (OOXML) / .XLSX malware analysis — malicious · b7b3d0f95948242d

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: db01bafeee5a915edaaacf9a8c66ef59 SHA-1: fae40d88b864852b8c4afc5c5e6737e61b8324c9 SHA-256: b7b3d0f95948242de085a5fc0125df73a92bd4981c6b0798bf8a2fc0da56e1cf

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristic firing indicates the presence of Excel 4.0 macros. The embedded macro sheet contains a string that appears to be a directory path, 'C:\ProgramData\fnsfunsgfgnkjfsgnd', which is likely used to stage or execute a malicious payload. The macro's intent is to run commands, suggesting it acts as a downloader or initial execution vector 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` `7a5e0b2cfc8f6b7da8a05f6f6ab22b6fc0afb0ed68967ff88c67a2a9b3bea052`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	4360 bytes

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