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

Static analysis result for SHA-256 638427e622c7af9d…

MALICIOUS

Office (OLE) / .XLS

985.0 KB Created: 2023-03-05 04:41:20 Authoring application: Microsoft Excel First seen: 2023-03-06
MD5: 2b78cbb69c4f6feb4738f5465d5bbc2b SHA-1: eb0f114b529ec37e900521c853076cd4ee6e13fb SHA-256: 638427e622c7af9deedc65183f58fc0c5d64c8ba1161d20061585429b4f4bc90
328 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1105 Ingress Tool Transfer T1204.002 Malicious File

The critical heuristic OLE_VBA_DOWNLOAD and the presence of a Workbook_Open macro indicate that the Excel file is designed to download and execute a payload. The VBA script contains calls to URLDownloadToFileA and ShellExecuteA, confirming the intent to download and run a second-stage artifact. The ClamAV detection further supports its malicious nature.

Heuristics 8

  • Reference to URLDownloadToFile API critical SC_STR_URLDOWNLOAD
    Reference to URLDownloadToFile API
  • URLDownloadToFile in VBA critical OLE_VBA_DOWNLOAD
    URLDownloadToFile in VBA
  • ClamAV: Xls.Malware.Valyria-10028013-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Malware.Valyria-10028013-0
  • Reference to ShellExecute API high SC_STR_SHELLEXEC
    Reference to ShellExecute API
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open macro
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
  • VBA macros detected medium OLE_VBA_MACROS
    Document contains VBA macro code
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
7686efc6e73476f11207700cd28ea7937223c9aea9c8384b0c3103bd6c4c6daf		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 9780 bytes

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