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

Static analysis result for SHA-256 a8edfd808c0c30de…

MALICIOUS

Office (OOXML) / .XLSX

86.2 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: bb6456b2119cd5597d4c5095822b78a0 SHA-1: 6dff6f559d93d16b1c5266ee4663fe592061146b SHA-256: a8edfd808c0c30de4cd92a88528896b199611715c77758644fbf4ccfdcc113d4
60 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The critical heuristic firing indicates the presence of Excel 4.0 macros within an XLSX file. Analysis of the macro sheet reveals commands that appear to construct a path to 'C:\ProgramData\Agent\a.exe', suggesting the macro's purpose is to download and execute a second-stage payload. The macro content is heavily obfuscated and truncated, limiting further analysis and confidence in family attribution.

Heuristics 1

  • 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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.bin
b929676af4c6b91ca3361b96958d4e9d0045f5debced808c6b6f4156a6633062		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 7475 bytes

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