Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 4fbd61c3f10ba889…

MALICIOUS

Office (OLE)

36.0 KB Created: 2020-11-25 10:39:44 Authoring application: Microsoft Excel
MD5: 8b8bfaac3100d4c3794cbff794a4863e SHA-1: d7929aa841f2bb34dc8eaca1207db0a9e4fa8747 SHA-256: 4fbd61c3f10ba8892da5be151a14d34b6310791bbba0d802e66e112a5be49ec7
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding indicating automatic execution. The presence of dangerous formula APIs like RUN further suggests malicious intent. The macro sheet itself contains a large amount of obfuscated data, likely to hide the payload. The primary attack vector is likely spearphishing attachment, leading to client execution via the macro.

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
cae31ee5767b105ad20a456677fc64336d13598bf8c3d91dc223b6ea3c9a7c24
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6503 bytes