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

Static analysis result for SHA-256 73633e1552e9b4e4…

MALICIOUS

Office (OLE) / .XLS

3.21 MB Created: 2012-03-06 05:26:30
MD5: bcab022602dfb2638431a452a4865a18 SHA-1: c18a51d766412ba768dfa317bd5d406c10a45123 SHA-256: 73633e1552e9b4e47625927585034d137235580e9b76f48e9ae615bee1004357
442 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1566.001 Spearphishing Attachment

The sample is an Excel file containing heavily obfuscated VBA macros. The Workbook_Open event triggers a loader that uses WScript.Shell and CreateObject to execute arbitrary code, likely to download and run a second-stage payload from the embedded URL http://www.frez.co.uk. The use of WScript.Shell and Shell() calls indicates command execution capabilities.

Heuristics 11

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
  • 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.
  • 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
  • GetObject call high OLE_VBA_GETOBJ
    GetObject 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
  • 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://www.frez.co.uk

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
cfde38eab9d1158a81da4f2ad6593d8ec1428a454558a368206f9ec0d13c06e0		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 3037969 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s).

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