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

Static analysis result for SHA-256 57d6d151077d0f68…

MALICIOUS

Office (OOXML) / .XLSX

100.4 KB Created: 2021-06-03 15:24:06 UTC Authoring application: Microsoft Excel 16.0300
MD5: 4a4e58b06056b8cde9bcfc15cefe1835 SHA-1: a485b82ebda5dc40830d575ccaf8bc18b65fc9da SHA-256: 57d6d151077d0f6855419881cf176e4f9c723e20132c2aff37f1dd85d30cb907
120 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The file is an Excel spreadsheet containing Excel 4.0 macros, which are known to be used for malicious purposes. The macros contain a call to `CreateObject` and execute `cmd`, indicating an attempt to run arbitrary commands. This suggests the file is a downloader or dropper for further malicious activity. The VBA code includes obfuscation to remove specific characters from strings, but the core functionality of executing a command via `cmd` is clear.

Heuristics 3

  • 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. The macro sheet is stored as XLSB/BIFF12 binary content, which many XML-only OOXML scanners miss.
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • VBA project inside OOXML medium OOXML_VBA
    Document contains vbaProject.bin — VBA macros present

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
e8a37e6897b47e8a1ade83918882e25425a14f29f9a8d28cfb5483e701f75849		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 654 bytes
vbaProject_00.bin
6dff422d2d807aa6e2e21f94db7ac1bc9584f1562225d94b68773938abee66b0		 vba-project OOXML VBA project: xl/vbaProject.bin 12288 bytes
xlm_sheet_00.bin
e09a73d820eac5470cbbcdd353d210327b365cd3443e9745e72d522a38816e2a		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 2138 bytes

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