Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 59414c20d13662f0…

MALICIOUS

Office (OLE)

35.5 KB Created: 2020-11-27 11:42:10 Authoring application: Microsoft Excel
MD5: 57511cc821c6ffb025f8fb92d572fa17 SHA-1: ec2379d5329d172e3d9c1dba840493ee29cd0868 SHA-256: 59414c20d13662f07a968c662d273692056d64cf04452f6ed487c7c1714ab20a
140 Risk Score

Malware Insights

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

The file is an Excel 4.0 macro-enabled workbook containing an Auto_Open function. This function is designed to execute dangerous formula APIs, including the RUN function, which is highly indicative of an attempt to download and execute a secondary payload. The obfuscated document body and the presence of numerous string constants in the macro script further suggest malicious intent.

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
32c6e8ff04ffc79da00f44fa0c081e639926050c73d3e3ced62b6a93db65ed55		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6705 bytes

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