Valyria — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 bfccfc780939495b…

MALICIOUS

Office (OLE) / .XLS

799.5 KB Created: 2018-12-06 20:43:11 Authoring application: Microsoft Excel
MD5: 25a858f2dcda04cc0a17dd72eaa314eb SHA-1: f77d0b7ff777c3ebd61122e4e589adf9d7aa54d3 SHA-256: bfccfc780939495bac476d88518df6f8206d669ba827d61c9a53ccb543ce5b9f
400 Risk Score

Malware Insights

Valyria · confidence 70%

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 User Execution: Malicious File T1059.001 Command and Scripting Interpreter: PowerShell

The sample is a malicious Excel file containing a VBA macro that uses Workbook_Open to automatically execute. The script is heavily obfuscated using large arrays of numeric values, making the exact payload delivery mechanism (e.g. a specific URL) unavailable for extraction. However, the heuristic firings for Shell() and WScript.Shell are clear indicators of intent to execute external commands. The family attribution is based on the ClamAV detection 'Xls.Malware.Valyria-10032137-0'.

Heuristics 9

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
  • ClamAV: Xls.Malware.Valyria-10032137-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Malware.Valyria-10032137-0
  • Reference to Windows Script Host high SC_STR_WSCRIPT
    Reference to Windows Script Host
  • 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.
  • Suspicious extracted artifact high 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.
  • 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
dd2962ee67e7a4a224a9c22ae8b0cda436d09636ca8f5e677cb40d4f72426800		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 245232 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 shell/COM execution token(s). Carved artifact contains 69 long base64-like blob(s). Carved macro source contains an auto-exec entry point and execution/download terms.

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