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

Static analysis result for SHA-256 2c215592f60b2151…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:43:13 Authoring application: Microsoft Excel
MD5: 4f13582b2917ec56388f8cbe6f35cea0 SHA-1: 3391dbb41757254d0c120e8fd8ef1d4e445301ab SHA-256: 2c215592f60b21510048459306d1526de2b17c9a318c593d5bec94a35067bfa3
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN indicate the presence of Excel 4.0 macros with an Auto_Open entry, which is a common technique for initial execution. The macro sheet contains a reference to 'Auto_Open' and uses dangerous functions like RUN, suggesting it's designed to execute arbitrary code. The extensive, obfuscated document body text does not provide clear user-facing content but likely serves to obscure the malicious macro's presence. The primary intent appears to be the execution of a second-stage payload via the RUN function.

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.
  • 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.
  • 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
007449488b661b4c291636d921508c145e55388b3e431f862586c136f3c0ebd6
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6436 bytes