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

Static analysis result for SHA-256 de91f05a84e729a0…

MALICIOUS

Office (OLE) / .XLS

2.41 MB Created: 2022-08-25 05:25:43 Authoring application: Microsoft Excel First seen: 2022-09-21
MD5: b8cdc170848ed8716de3653a5f1e533f SHA-1: a0aaa393f3bf5774987c8a38352e457f5f6db0b2 SHA-256: de91f05a84e729a06343d0172006b6b30aed68283b6e998d6ca170ab47294f61
272 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.003 Windows Command Shell T1105 Ingress Tool Transfer

The Workbook_Open macro is heavily obfuscated and uses CreateObject to execute commands. It attempts to delete several files and then constructs a path to download a zip file. The presence of an obfuscated auto-exec loader and the ClamAV detection strongly indicate malicious intent, likely to download and execute a secondary payload.

Heuristics 9

  • Obfuscated auto-exec VBA loader critical OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER
    Auto-exec VBA reconstructs strings with a heavy custom decoder (numeric char-array, repeated hex-string decode, or junk-token Replace removal) and feeds them to a COM-instantiation or execution sink. This obfuscated-loader shape keeps CreateObject/Shell/URL indicators out of the macro source.
  • ClamAV: Xls.Malware.Sload-7135989-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Malware.Sload-7135989-0
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open macro
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • 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)
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://ns.adobe.com/xap/1.0/
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/xap/1.0/sType/ResourceRef#

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
ca075ec7448504b9885cb0040e01ff9598d5139808acd1cef7dcf80192365f70		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 56144 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 20 long base64-like blob(s).

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