Malicious Office (OOXML) / .XLSM — malware analysis report

Static analysis result for SHA-256 7c2dce53d23d62b4…

MALICIOUS

Office (OOXML) / .XLSM

33.7 KB Created: 2021-03-10 13:44:24 UTC Authoring application: Microsoft Excel 16.0300
MD5: f685aa869cf29499b615dff5c4b5f9f8 SHA-1: 2d461fa264897b3edb0e5d79b5e7d76c2c5b62c6 SHA-256: 7c2dce53d23d62b45470c002311761fc35f78d2af8b0052dcdd0362206d986fa
210 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1059.001 PowerShell T1204.002 Malicious File T1105 Ingress Tool Transfer

This Excel macro-enabled document (XLSM) utilizes Excel 4.0 macros, which are known for their ability to bypass security features and directly call Win32 APIs. The heuristic firings indicate the use of dangerous XLM formula APIs like RETURN, and the presence of a VBA project suggests a multi-stage approach. The VBA script contains a call to URLDownloadToFileA, which is used to download and execute a second-stage payload from a remote location. The document body contains heavily obfuscated text that does not provide clear user-facing content, further suggesting a malicious intent.

Heuristics 6

  • URLDownloadToFile in VBA critical OLE_VBA_DOWNLOAD
    URLDownloadToFile in VBA
  • 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: 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.
  • 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.

FilenameKindSourceSize
macros.bas
bcc8c92fa0ea61ae34bd5ebab055d747b47678b77a3e38cfc90e4eda43588bb7		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 3050 bytes
vbaProject_00.bin
d9af2f44bbba69821d13c891f08b2573ae22256fbe7f9aa4390bc6f3ad4443d1		 vba-project OOXML VBA project: xl/vbaProject.bin 25088 bytes
xlm_sheet_00.xml
1e633e5755f964e146eb49f60f198990f17dc64877cf12597e720e6877ce422e		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 919 bytes

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