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

Static analysis result for SHA-256 58704811385cc8b6…

MALICIOUS

Office (OLE) / .XLSX

236.5 KB Created: 2020-05-21 08:12:32 Authoring application: Microsoft Excel
MD5: 3b2c73b0e3587103d32e65045b071d5b SHA-1: 62a1dceeefa0567d2da741e008fd2efe0165651c SHA-256: 58704811385cc8b6df07aa2811e35372ef33ee0fddd9556340339cd99ed2db94
200 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file contains Excel 4.0 macros, specifically an obfuscated Auto_Open execution chain. This indicates the file is designed to automatically run malicious code upon opening. ClamAV detection confirms its malicious nature, identifying it as Xls.Dropper.Agent-8009519-0. The macro execution chain is designed to download and execute a second-stage payload.

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-8009519-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.Agent-8009519-0
  • 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
8948e90ac6f5ad147d3b049fbe78c32c4048881058ae09a6cc1db368b1796990		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 129046 bytes

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