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

Static analysis result for SHA-256 c6b6939c90c6aa42…

MALICIOUS

Office (OLE) / .XLSX

130.5 KB Created: 2013-10-22 08:38:00 Authoring application: Microsoft Excel
MD5: 40480e98fb26e00335d4de455234e26c SHA-1: a355f65099ec592c7bcabe4e3a99cd39ee892cae SHA-256: c6b6939c90c6aa429a3dedda66faa9d14d23b378994f81b62648275455a8e1ba
140 Risk Score

Malware Insights

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

The critical heuristic OLE_XLM_AUTOOPEN_DEFINEDNAME indicates the presence of an Excel 4.0 Auto_Open macro. The OLE_XLM_DANGEROUS_FN heuristic further confirms that this macro uses dangerous functions, specifically 'RUN', which is commonly used to execute arbitrary commands or download additional payloads. The presence of an encrypted document body suggests an attempt to obscure the malicious content. The macro sheet itself contains numerous incomplete formula parsing errors, indicating potential obfuscation or corruption.

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
aee238a86cc5b6c3a6e91d71f62f6849881c1a9e6076be040b3e054ab8016b00
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 73587 bytes