Office (OOXML) / .XLSM malware analysis — malicious · 440b905205a4cbd2

MALICIOUS

Office (OOXML) / .XLSM

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

MD5: 18606255fd540890ad9058a6d1a6c1e2 SHA-1: 27200d04f93e540c047e2566a2f28c8ec32dfdb5 SHA-256: 440b905205a4cbd2004e99f8ead394b6dfbf2c840abc6b390a7bc4eccb0ccfd3

130 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic for Applications T1204.002 Malicious File T1059.001 PowerShell T1059.003 Windows Command Shell

The sample is an XLSM file containing Excel 4.0 macros. The critical heuristics indicate the use of dangerous XLM formula APIs such as FOPEN, FWRITE, and EXEC, which are commonly used to download and execute payloads. The reconstructed string 'C:\ProgramData\MzHS PvYIyhhHip.vb' indicates the likely path for the downloaded payload. The ALERT function call further suggests malicious intent by displaying a deceptive message.

Heuristics 4

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.
Dangerous XLM formula APIs: FOPEN, FWRITE, FCLOSE, EXEC, RETURN critical OOXML_XLM_DANGEROUS_FN

Excel 4.0 macro sheet uses formula APIs that call directly into Win32 (=CALL/=EXEC/=REGISTER/=FORMULA). These are the primitives used to download payloads, write files, and start processes from an XLM macro without invoking VBA.
Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET

Excel workbook contains 1 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction
Embedded URL info EMBEDDED_URL

One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
URL http://schemas.openxmlformats.org/spreadsheetml/2006/main
- http://schemas.microsoft.com/office/excel/2006/main
- http://schemas.openxmlformats.org/officeDocument/2006/relationships

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.xml` `80d76a782903bb360a4a029c5013c8cb83c0ecd85318c17365e15cf9c5b53eb7`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.xml	5289 bytes

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