Malicious PDF — malware analysis report

Static analysis result for SHA-256 42abd150bdaab4f4…

MALICIOUS

PDF

61.7 KB Created: 2016-07-04 05:27:39 -05:00 Authoring application: WHMCS (via TCPDF 6.0.051 (http://www.tcpdf.org))
MD5: 97bfc7cdb2726ac3f403c187d6994da5 SHA-1: da097eda58b92a12525dcadc0b23f12313177669 SHA-256: 42abd150bdaab4f45f7bc7c23705ba1c1e8abf1fb4cca0a63d9d810278ae63ab
556 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File T1566.002 Spearphishing Attachment T1059.001 PowerShell T1204.001 User Execution: Malicious Link T1027 Obfuscated Files or Information

This PDF document contains embedded JavaScript that leverages a launch action to execute cmd.exe. The primary payload is an embedded Windows executable, masquerading as 'asd.pdf', which is designed to be dropped and executed. This is further supported by critical heuristic firings indicating a PDF launch action combined with an embedded PE payload and command execution. The ClamAV detection of 'Pdf.Dropper.Agent-7254798-0' and 'Win.Trojan.MSShellcode-7' on the extracted artifact confirms its malicious nature as a dropper.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 14

  • 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.
  • 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\\asd.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.
  • ClamAV: Pdf.Dropper.Agent-7254798-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Dropper.Agent-7254798-0
  • ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV
    ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
  • /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.
  • Clickable PDF combines external action with parser-evasion structure high PDF_ACTION_PARSER_EVASION
    PDF has an external clickable URI together with object graph or xref structures that make parsers disagree, such as divergent duplicate objects, parser divergence, or xref offset mismatch. That combination is stronger than a plain link: the document is both an outward-action carrier and a parser-confusion/evasion sample.
  • JavaScript action low 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
  • External URI info PDF_URI
    PDF contains an external URL action
  • 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.tcpdf.org
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/xap/1.0/
    • http://ns.adobe.com/pdf/1.3/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://www.aiim.org/pdfa/ns/extension/
    • http://www.aiim.org/pdfa/ns/schema#
    • http://www.aiim.org/pdfa/ns/property#
    • http://www.aiim.org/pdfa/ns/id/

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
asd.pdf
3c0554cfdef4fd8576d1e4f5426ef3570738f4cc9e5ccfb6dc4a44ec281d0102		 pdf-embedded-file PDF EmbeddedFile object 16 at offset 0x4444 73802 bytes
Detection
ClamAV: Win.Trojan.MSShellcode-7
Obfuscation or payload: unlikely
javascript_obj0017_000.js
9096c5f1fbddce877ede1aad80c32e314bc0ce9949af408e1815fde678f243e3		 pdf-javascript-stream PDF /JS object 17 at offset 0xF0BE 52 bytes

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