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

Static analysis result for SHA-256 28e37053ad15ea80…

MALICIOUS

Office (OLE) / .XLS

45.5 KB Created: 2020-10-30 08:53:19 Authoring application: Microsoft Excel
MD5: 739b6d81da07b988ab835fd22405a7d4 SHA-1: 431f14d759222ed8b112ef6fa3a0babf17d0566c SHA-256: 28e37053ad15ea80cc1ea5a4ccf248fbddd2bcb0d9eed572bd939ffae6a90483
180 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1564.001 Hidden Files and Directories

The sample is an Excel 4.0 macro-enabled spreadsheet. Critical heuristics indicate the presence of an Auto_Open defined name, which is a common technique for automatic execution of malicious code upon opening the document. The presence of a HALT gate suggests environment evasion. The macro sheet itself contains numerous obfuscated strings and labels, but the primary threat vector is the Auto_Open execution.

Heuristics 4

  • 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.
  • XLM Auto_Open environment-evasion HALT gate high OLE_XLM_ENVIRONMENT_EVASION_HALT
    Excel 4.0 macro sheet auto-executes multiple GET.WORKSPACE / GET.WINDOW environment checks and halts execution when the host does not match the expected user environment. This is a common sandbox-evasion pattern in XLM malware and is stronger than a bare XLM macro-sheet indicator.
  • 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
0f06db4e0983cb6c3ca02fb6b0cc1885a342dc10ecc81414ad98e569b5110d2b		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 13143 bytes

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