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

Static analysis result for SHA-256 381c6903595831d4…

MALICIOUS

Office (OLE) / .XLSX

71.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-06-07
MD5: 58ea07b0b94c9dadf7b9e7e9aea18e0e SHA-1: 12c2d66c399fd9a6ad3247c979469d2889fec5fb SHA-256: 381c6903595831d4638fe446d7f699401cc5f5d7146be5954813541b011eba73
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Service Execution T1059.001 PowerShell: PowerShell T1204.002 Malicious File: Malicious File

The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN indicate the presence of an Excel 4.0 macro with an Auto_Open function that uses dangerous APIs, specifically the RUN function. The macro sheet contains multiple URLs which are likely used to download and execute a second-stage payload. The presence of the RUN function strongly suggests the macro is intended to execute arbitrary code.

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
b15b1a7eda5b33086d8276c3ce6587701b6f26d4c243b84df03390c1913f7d50
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 7806 bytes