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

Static analysis result for SHA-256 5fd7a79524404cf9…

MALICIOUS

Office (OLE) / .XLS

105.5 KB Created: 2021-12-29 06:52:36 Authoring application: Microsoft Excel First seen: 2022-03-31
MD5: f7a5a485e1d47d772ef89d985884ddee SHA-1: a4ce19d2d1b13a026081edb4c55ee996187a5a3c SHA-256: 5fd7a79524404cf9c99108e696750a444c08a66a66228deddb32a3fb579a4e6f
320 Risk Score

Malware Insights

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

The Workbook_Open macro is triggered upon opening the Excel file, executing obfuscated VBA code. This code reconstructs a URL and attempts to download and execute a file named 'putty.exe' from that URL to the user's public directory. The use of CreateObject and Shell() calls indicates a downloader functionality.

Heuristics 7

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • 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: Doc.Downloader.DocuSign04220-9942585-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.DocuSign04220-9942585-0
  • 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
665f09781fb250e14f44733a22419dd8ce9101e4657189e6d85b9b27b07ab03f		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 9447 bytes

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