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

Static analysis result for SHA-256 61e08fbeee16298e…

MALICIOUS

Office (OOXML) / .XLSM

476.0 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 15.0300
MD5: b21bafd7f17bce416c198a95bf80dca6 SHA-1: 9cc786d45cf96e190299e653274b5fe25095f1e7 SHA-256: 61e08fbeee16298ea2bb3770d6766d7e15ce5a6253cc8e535ca82a9446f229e0
202 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1105 Ingress Tool Transfer

The sample is an Excel 4.0 macro sheet containing WinAPI and download strings, indicating it is designed to download and execute a second-stage payload. The macro sheet explicitly calls functions like DownloadToFileA and CreateDirectoryA, and references the URL http://149.3.170.144/gt-hot/web.exe to retrieve the payload. The presence of Auto_Open suggests automatic execution upon opening.

Heuristics 5

  • 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.
  • 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.
  • Binary XLM macro sheet with WinAPI/download strings critical OOXML_XLM_BINARY_WINAPI_STRINGS
    Excel 4.0 macro sheet is stored as BIFF12/XLSB binary data and contains Win32 download or process-execution API strings such as URLDownloadToFileA, ShellExecuteA, or CreateDirectoryA. These strings are high-signal in XLM macro sheets and catch payload-download macros that XML-formula scanners cannot parse.
  • NOP-equivalent sled detected medium SC_NOP_EQUIV_SLED
    Long run of 0x61 bytes
  • 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://149.3.170.144/gt-hot/web.exe

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