Malicious Office (OLE) / .XLS — malware analysis report

Static analysis result for SHA-256 eec38db940fd4abd…

MALICIOUS

Office (OLE) / .XLS

204.0 KB Created: 2020-07-01 23:17:53 Authoring application: Microsoft Excel
MD5: 3a0c341e3cc6d3fc0a313047b149445f SHA-1: 0dd5f649e45d8d5ae754b58c08f43b8c4f07c695 SHA-256: eec38db940fd4abda3e0d439c108c9fd9daa8e755b7bb111e1cf4f2071837b12
200 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The file is an Excel 4.0 macro-enabled spreadsheet. Critical heuristics indicate the presence of an Auto_Open macro, which is configured to execute dangerous functions and includes environment evasion techniques. The macro sheet itself contains numerous obfuscated strings and sheet names, suggesting it is designed to run arbitrary code upon opening. The presence of the Auto_Open function and the use of dangerous APIs strongly suggest this macro is intended to download and execute a second-stage payload.

Heuristics 4

  • Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME
    oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
  • XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
  • XLM Auto_Open environment-evasion close gate critical OLE_XLM_ENVIRONMENT_EVASION_CLOSE
    Excel 4.0 macro sheet auto-executes environment checks with GET.WORKSPACE / GET.WINDOW, then shows a fake corruption/error message and closes the workbook when the host fails those checks. This is a malware sandbox-evasion pattern, even when the later payload stage is hidden behind obfuscated defined-name flow.
  • Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
    Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
cc0a24119157896abb72694b4e38aa345e91e4c48c448483ffc635938cd6143c		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 81380 bytes

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