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

Static analysis result for SHA-256 93ae70599f085617…

MALICIOUS

Office (OOXML) / .XLSX

64.9 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: b67d28863f69d41496acb405b0daef0f SHA-1: 99993f9fa5904454b32818e7b4bd4552f2bb40da SHA-256: 93ae70599f085617b2fd3f302b77f807142ec79b94b6fdd30c7fda9493aee68b
182 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1059.001 PowerShell T1059.003 Windows Command Shell T1105 Ingress Tool Transfer

The sample is an Excel 4.0 macro sheet that utilizes WinAPI functions like URLDownloadToFileA to download files from the provided URLs. The script's intent is to download and execute a second-stage payload. While the URLs themselves are marked as benign, the presence of macro code designed for downloading and executing external content indicates a malicious intent. The specific payload downloaded is not discernible from the provided evidence.

Heuristics 4

  • 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.
  • 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.
  • URL reconstructed from XLM cell array (3 URLs) critical OOXML_XLM_CELL_ARRAY_URL
    Excel 4.0 macro sheet stages its payload URL across individual numeric cells (one ASCII charcode per cell) or inside an embedded HTA that uses VBScript Chr()/&-concat obfuscation. The reconstructed URL is invisible to literal-bytes URL extraction because it is never contiguous in the workbook stream. URLs were recovered by walking the BIFF12 record stream of every worksheet and macrosheet part and decoding RK/inline-string cells in both row-major and column-major order.
  • 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 https://cdn.discordapp.com/attachments/911249881849536584/912356067688714250/cvVactCffEgjaSvpshekniggagook.flac
    • https://cdn.discordapp.com/attachments/911249881849536584/912356058922614854/CVjrWfYwLXUpshekniggagook.flac
    • https://cdn.discordapp.com/attachments/911249881849536584/912356063758675998/GjEdowscAmeMpshekniggagook.flac

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.bin
ef4bbba5cf5579939cbb253b08d8bd62a5c1df0d2815149924d557872cd5b138		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 4951 bytes

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