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

Static analysis result for SHA-256 787df34b3b6bf03e…

MALICIOUS

Office (OOXML) / .XLSM

921.5 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: 3da847ab9e370416510af015cb6e304c SHA-1: 538a570c6ae2efed34355a6b6250ac768ab6e459 SHA-256: 787df34b3b6bf03e92479e3f1a5a78d346e977469e36278c7d428542e2c0a83d
330 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 Malicious File

This XLSM file contains Excel 4.0 macros, including an Auto_Open macro, and uses dangerous functions like CALL, EXEC, and REGISTER. The presence of a macro-enable lure indicates an attempt to bypass security controls. The heuristics suggest the macros are designed to download and execute a second-stage payload, but no specific URLs or hashes were extracted to confirm this.

Heuristics 9

  • Excel 4.0 macro sheet (3 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.
  • Excel 4.0 Auto_Open defined name critical OOXML_XLM_AUTOOPEN_DEFINEDNAME
    Workbook defines _xlnm.Auto_Open or _xlnm.Auto_Close while containing an XLM macro sheet. This is the OOXML/XLSB auto-execution shape for Excel 4.0 macros.
  • Dangerous XLM formula APIs: GOTO, EXEC, 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.
  • PEB access via FS segment (x86) high SC_PEB_ACCESS
    PEB access via FS segment (x86)
  • Reference to LoadLibrary API high SC_STR_LOADLIBRARY
    Reference to LoadLibrary API
  • Reference to GetProcAddress API high SC_STR_GETPROCADDRESS
    Reference to GetProcAddress API
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings
  • 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 — context-specific rules above attribute URLs they actually evaluated; this rule lists URLs that were present in the bytes but were not otherwise tied to a specific finding.
    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
    • http://schemas.microsoft.com/office/excel/2006/main
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision6

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
16906c43ea71e7ceb95d2718eec32533a2cb6af3357ce8a6142e8a664da0db88		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1750 bytes
xlm_sheet_01.xml
36317a1726fcc0ea4f4b9877cdd923b9a162e77bfb18441186d29aec7144a8de		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 1855 bytes
xlm_sheet_02.xml
31f588c7324c4e72af751bb0a95a8d409e0841c96318e2fa41d7e0a83f2289dc		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet3.xml 2339 bytes

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