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

Static analysis result for SHA-256 0b41ad678426a471…

MALICIOUS

Office (OOXML) / .XLSM

923.8 KB Created: 2019-02-25 18:42:45 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2025-02-23
MD5: 3fb5b7244e5d9286c12da9c45d32e206 SHA-1: 271d3f99c65b8ff3c1b350cc99ace17a41eccf17 SHA-256: 0b41ad678426a4712683dc4f7693b3b94554b5f9b68beef945b6b699b61822a7
208 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1566.001 Spearphishing Attachment T1059.005 Visual Basic

The Workbook_Open macro executes a PowerShell command that appears to download and execute a second-stage payload. The PowerShell command is obfuscated by reassembling API names from split string literals, specifically 'powershell'. The macro also uses CreateObject, a common technique for launching external processes. The overall intent is to download and run additional malicious code.

Heuristics 6

  • Dangerous API name reassembled from split string literals critical OLE_VBA_SPLIT_KEYWORD_OBFUSCATION
    VBA concatenates short string literals that reassemble a dangerous API/ProgID/LOLBin name (e.g. Scripting.FileSystemObject, WScript.Shell, powershell, URLDownloadToFile) which appears in no single literal. Splitting an API name across string concatenation is done only to evade keyword scanning.
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open macro
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
  • VBA project inside OOXML medium OOXML_VBA
    Document contains a VBA project — 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

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
b330f7de9f95a42b24322525d916986fa6244e794288afaa5b7b3aa4703361a1		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 24631 bytes
vbaProject_00.bin
c47ca1aed6020dd25ba07661940011d6db20157e5d11a842d582b3556e712092		 vba-project OOXML VBA project: xl/vbaProject.bin 75264 bytes

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