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

Static analysis result for SHA-256 e9aa61cbd009d086…

MALICIOUS

Office (OLE) / .XLS

55.0 KB Created: 2020-10-28 08:15:02 Authoring application: Microsoft Excel
MD5: 36e85e8360324d90295945553cd6a399 SHA-1: a28de63169e1a6223f88d05285daeb7fb0c39b3c SHA-256: e9aa61cbd009d086eacc15d635cb3afd446ad6e23f652c4a6655769b7fdc1b23
180 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. Heuristics indicate the presence of an Auto_Open macro and the use of dangerous functions like RUN, suggesting it's designed to execute commands upon opening. The macro sheet also contains environment evasion checks. While no specific payload URLs or hashes were extracted, the Auto_Open function with the RUN command strongly implies the execution of 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 HALT gate high OLE_XLM_ENVIRONMENT_EVASION_HALT
    Excel 4.0 macro sheet auto-executes multiple GET.WORKSPACE / GET.WINDOW environment checks and halts execution when the host does not match the expected user environment. This is a common sandbox-evasion pattern in XLM malware and is stronger than a bare XLM macro-sheet indicator.
  • 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
6fe65de4dd5a6ced84bab9533bf2507e5fc137aae7d8257e4234a0c2d4215771		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 16664 bytes

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