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

Static analysis result for SHA-256 8f628f5cb87048d4…

MALICIOUS

Office (OOXML) / .XLSM

46.7 KB Created: 2020-05-17 14:23:36 UTC Authoring application: Microsoft Excel 16.0300
MD5: 10dbe01a0b7972bfd0e1333ce16870a6 SHA-1: a3fee9cc699c024af5b98924801f098ad278e9f5 SHA-256: 8f628f5cb87048d48e0ce7190b6d88cffcb7d2a95b589677bb40db06e64e569b
128 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1204.002 Malicious File: User Execution: Malicious File T1059.001 Command and Scripting Interpreter: PowerShell T1059.003 Command and Scripting Interpreter: Windows Command Shell

This XLSM file contains Excel 4.0 macros, which are known to be used for malicious purposes. The heuristics indicate the use of dangerous XLM functions like RUN and CALL, which can be used to execute arbitrary code. The presence of hidden sheets and the extraction of an XLM macro sheet further support this. The primary attack vector appears to be the execution of these macros, which likely download and execute a second-stage payload.

Heuristics 5

  • Dangerous XLM formula APIs: RUN, CALL, HALT 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.
  • Suspicious extracted artifact medium EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 24 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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
85e7635e064a50dfbcc6bf501f632f819c07619c7c194c3a0968869b4e9372b6		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 64418 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 shell/COM execution token(s).

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