Office (OOXML) / .XLSM malware analysis — malicious · 554783223e23221a

MALICIOUS

Office (OOXML) / .XLSM

37.6 KB Created: 2021-03-30 07:11:12 UTC Authoring application: 16.0300

MD5: fef534b184aef7a29a1d957367a3df26 SHA-1: f561acc1b67b2efd5c4c7bf342567d599adcc851 SHA-256: 554783223e23221ac3572f3c31f2a1fe6f543aca41d61ec11fc3e04b953b7956

88 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic for Applications T1059.001 PowerShell

The sample is an XLSM file containing Excel 4.0 macros, a known technique for delivering malware. The presence of a hidden sheet further suggests an attempt to conceal malicious activity. While the document body is heavily obfuscated and unreadable, the critical heuristic firing on XLM macros indicates the primary mechanism for execution. The macros likely download and execute a second-stage payload, though the specific URLs are benign schema references.

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.
VBA project inside OOXML medium OOXML_VBA

Document contains vbaProject.bin — VBA macros present
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
- http://schemas.openxmlformats.org/markup-compatibility/2006
- http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac

Extracted artifacts 3

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas` `6ac6d5faf1e22f6b580123470222be8cac4477471039d83c9a75fe34c7f08e09`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	2329 bytes
`vbaProject_00.bin` `fd75e5bfbda3981bd72d703759d3916661b4d3b07800eb1692668f5b956c43a2`	vba-project	OOXML VBA project: xl/vbaProject.bin	20480 bytes
`xlm_sheet_00.xml` `c16e4cde2e69a3814f7e22498b8268ba35cc6459c7512f025029178c7ba2c2ba`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.xml	763 bytes

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