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

Static analysis result for SHA-256 d79f4a7d726e301b…

MALICIOUS

Office (OOXML) / .XLSM

80.2 KB Created: 2021-02-10 12:29:58 UTC Authoring application: Microsoft Excel 16.0300
MD5: daad097831bd0e8d2cbc32e24ed078cc SHA-1: 858163b22559297d5d82a077e6f217cc40d7f95a SHA-256: d79f4a7d726e301bfe7832472ccf9786b52d01fcc6b3abb23379a076764f76da
188 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 XLSM file contains Excel 4.0 macros, which are known to be used for malicious purposes. The critical heuristic 'OLE_VBA_DOWNLOAD' indicates the use of URLDownloadToFile, suggesting the macro attempts to download a payload. The 'OOXML_XLM_DANGEROUS_FN' heuristic further confirms the use of dangerous XLM formula APIs like CALL, EXEC, and REGISTER, which can be used to execute arbitrary code. The presence of hidden worksheets also suggests an attempt to conceal malicious activity. The overall pattern points to a downloader utilizing legacy Excel macro capabilities.

Heuristics 6

  • URLDownloadToFile in VBA critical OLE_VBA_DOWNLOAD
    URLDownloadToFile in VBA
  • 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.
  • Excel 4.0 macro sheet (1 sheet(s)) high 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 4 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.openxmlformats.org/officeDocument/2006/relationships
    • http://schemas.openxmlformats.org/markup-compatibility/2006
    • http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac
    • http://schemas.microsoft.com/office/spreadsheetml/2014/revision
    • http://schemas.microsoft.com/office/spreadsheetml/2015/revision2
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision3

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
93dd6a04e1c8847dc3bcb46aa910b0b6f137bb36204e9deaa7e2933cbbc93734		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 3924 bytes
vbaProject_00.bin
dd5e5754af0f557acfdd5eb7cf7ef20388e54fb24877783f24b33ed52f2c64c1		 vba-project OOXML VBA project: xl/vbaProject.bin 25600 bytes
xlm_sheet_00.xml
98b88d69c25caa122d23561f0fe5a23f7f2800fa05fd3acfeaabfc008b6485da		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1425 bytes

Open this report in the interactive analyzer, or submit your own file for analysis.