Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 ac8d31a69f5c96b5…

MALICIOUS

Office (OOXML)

11.0 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: 2c91dfb12bba0bdef72d43284114e497 SHA-1: 1261258d8cef60a5d53be8f2a3ff1cd6f540ef7f SHA-256: ac8d31a69f5c96b5e58f93f3f0febbf143f56ec4e63e17faaa290c0ab78804f7
220 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

The sample is an OOXML document containing a VBA macro with an Auto_Open subroutine. This subroutine uses string concatenation to obfuscate the command 'powershell' and then executes it using the Shell() function. This indicates an attempt to download and execute a second-stage payload.

Heuristics 5

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • Dangerous API name reassembled from split string literals critical OLE_VBA_SPLIT_KEYWORD_OBFUSCATION
    VBA concatenates short string literals that reassemble a dangerous API/ProgID/LOLBin name (e.g. Scripting.FileSystemObject, WScript.Shell, powershell, URLDownloadToFile) which appears in no single literal. Splitting an API name across string concatenation is done only to evade keyword scanning.
  • Auto_Open macro high OLE_VBA_AUTO
    Auto_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 project inside OOXML medium OOXML_VBA
    Document contains a VBA project — VBA macros present

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
d409352b17312cfbe60d2d28076cf6b6df050051f3b1eb02e57d3ca113d9ff18		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 759 bytes
vbaProject_00.bin
026661d5111f3245ca347d5e3f4a471b0cf620f828b2827400106f44b7d44b1e		 vba-project OOXML VBA project: xl/vbaProject.bin 10240 bytes

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