Office (OOXML) / .XLSM malware analysis — malicious · 582f2b77cf9f80dd

MALICIOUS

Office (OOXML) / .XLSM

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

MD5: ff46051b82db9f45e6cb9b9cf8767b97 SHA-1: 2bce24314d58c9fd6cf18ee50bb292c7f5b4d2c1 SHA-256: 582f2b77cf9f80dd31a175e417f18f0e8a35a6a824a89d9ac6335753b88bb25e

130 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File T1105 Ingress Tool Transfer

This XLSM file contains Excel 4.0 macros, which are known to be used for malicious purposes. The macros utilize dangerous functions like FOPEN, FWRITE, and FCLOSE to write a file to disk, and EXEC to run it. The reconstructed filename is 'C:\ProgramData\LIYZvHQ..vb s'. This indicates a downloader or dropper functionality, aiming to execute a second-stage payload.

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` `53778d331263b2c3fe505d510a4208547dee37327e821eb2d1910408f74e6bec`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.xml	6311 bytes

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