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

Static analysis result for SHA-256 e0ea6248ee6384fe…

MALICIOUS

Office (OLE) / .XLSX

235.0 KB Created: 2020-05-21 07:39:23 Authoring application: Microsoft Excel
MD5: c6528ef942b2c3a4e85465584c9254b5 SHA-1: 537dde326cc1cb28fcea64b122eee691b86d4b1e SHA-256: e0ea6248ee6384fe5f77d44d06943d43ae8f06e5990e3ef676193c7ce47351de
200 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1566.001 Phishing: Spearphishing Attachment

The file is identified as malicious by ClamAV and exhibits critical heuristic firings related to obfuscated Excel 4.0 macros, specifically an Auto_Open execution chain. The macro uses a series of `FORMULA(CHAR(...))` calls, indicating an attempt to construct and execute a command or payload. This suggests the file acts as a dropper, designed to download and execute a second-stage payload. The obfuscation techniques used in the macro are a strong indicator of malicious intent.

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.
  • Obfuscated XLM Auto_Open execution chain critical OLE_XLM_OBFUSCATED_AUTOEXEC_CHAIN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and an obfuscated formula execution chain. The macro builds strings through FORMULA(CHAR(...)), primes state with SET.VALUE / GET.CELL / GOTO, and transfers control through RUN(). This is a high-confidence XLM malware pattern.
  • ClamAV: Xls.Dropper.Agent-8009524-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.Agent-8009524-0
  • 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
1ebbe0f4a35b48e8680a9e0749d8c9dea2dabadb554a62027ed8a2936c71ba44		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 128650 bytes

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