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

Static analysis result for SHA-256 dc23c0d9e4e6b63b…

MALICIOUS

Office (OLE) / .XLS

54.5 KB Created: 2020-10-28 08:15:02 Authoring application: Microsoft Excel
MD5: 8e233c3b23044c29d172fd33a8d59c90 SHA-1: d886313c682b82234d57d61231514246554de465 SHA-256: dc23c0d9e4e6b63bb76f3ec1bb74879999d25c5d2d664a8f009f0b1757a92fd1
180 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

This Excel file contains Excel 4.0 (XLM) macros, indicated by the OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN heuristics. The presence of an 'Auto_Open' defined name signifies that the macro will execute automatically when the workbook is opened. The OLE_XLM_ENVIRONMENT_EVASION_HALT heuristic suggests the macro attempts to evade detection. The primary function of the XLM macro appears to be the execution of dangerous API calls, including 'RUN', which is commonly used to download and execute further malicious content.

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
1feb1ba29aed34b5ba389cc93dfd7b18b8e2dafa80d4146ef97a38e2e441a70f		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 16671 bytes

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