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

Static analysis result for SHA-256 47c4119f089d1419…

MALICIOUS

Office (OLE) / .XLSX

316.5 KB Created: 2020-05-20 11:13:50 Authoring application: Microsoft Excel
MD5: 86edd17a745cc5602e0d36e30b8c2f76 SHA-1: c22f0b3d1b8b5b15e4b22efc8b269c28902c62c9 SHA-256: 47c4119f089d1419560fd01cae0e04b88821675792aeb739bea1864838a48c14
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic

The file contains an Excel 4.0 macro sheet with an Auto_Open entry, which is a common technique for initial execution. The heuristics indicate that the Auto_Open chain is obfuscated, suggesting an attempt to evade detection. The macro itself appears to be truncated, making it difficult to determine the exact payload or further execution steps.

Heuristics 3

  • 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.
  • Obfuscated XLM Auto_Open execution chain critical OLE_XLM_OBFUSCATED_AUTOEXEC_CHAIN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and an obfuscated formula execution chain. The macro builds strings through FORMULA(CHAR(...)), primes state with SET.VALUE / GET.CELL / GOTO, and transfers control through RUN(). This is a high-confidence XLM malware pattern.
  • 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
9609b144fc82eb48dfd636ecb4a75c3429967c20583af0009679bae52d8c657f		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 126379 bytes

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