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

Static analysis result for SHA-256 110274409ed0ad8c…

MALICIOUS

Office (OLE) / .XLSX

316.5 KB Created: 2020-05-20 11:47:10 Authoring application: Microsoft Excel
MD5: 8b2cb3cbe2d59d9082f97c162a1fca67 SHA-1: f613fe4c7a4bbb9589af645190ac00d9d5030fda SHA-256: 110274409ed0ad8c16f7bdbab1bd81eabb97ffbcf4a8607007db0b00e96226b1
140 Risk Score

Malware Insights

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

The sample contains an Excel 4.0 macro sheet with an Auto_Open entry, indicating an attempt at automatic execution upon opening. The heuristics indicate an obfuscated execution chain involving formulas and state transfers, typical of macro-based malware designed to download and execute a second-stage payload. The specific obfuscation techniques suggest a malicious intent to bypass detection.

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.
  • 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.
  • 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
edbb9cd78217b52970bf1e4b2c0820100487d620003a456c5275e0dee9b590d0		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 125470 bytes

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