Malicious PDF — malware analysis report

Static analysis result for SHA-256 71c35ec90a6b302c…

MALICIOUS

PDF

535.1 KB
MD5: 5ea3eaedef49173de3a7763449292364 SHA-1: a685c1cf944e458a17898648d21191a44a7b027a SHA-256: 71c35ec90a6b302c84995fcd057e3123f4f7ad04ba75c1d64f74c528d2d20dda
154 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The PDF file contains embedded JavaScript and triggers multiple PDF-specific exploit heuristics, including XFA form exploitation and the use of String.fromCharCode. The deobfuscated JavaScript indicates an attempt to download and execute a second-stage payload. The presence of the URL http://www.bitstream.com is noted, though its reputation is unknown.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9926

Heuristics 9

  • PDF JavaScript exploit cluster critical PDF_JS_EXPLOIT_CLUSTER
    PDF combines an executable JavaScript/action surface with exploit staging indicators such as eval/unescape/fromCharCode, XFA script content, or a related CVE pattern. Benign form JavaScript remains low-severity, but this correlated cluster is high-confidence malicious behavior.
  • ASCIIHexDecode filter (with exploit indicators) medium PDF_FILTER_HEX
    Hex-encoding filter present alongside exploit delivery indicators — often used to hide payload or shellcode bytes
  • 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.
  • XFA form low PDF_XFA
    PDF uses XML Forms Architecture — can contain script logic
  • String.fromCharCode low PDF_FROMCHARCODE
    String.fromCharCode found — used to construct payload strings dynamically. Common in benign JavaScript libraries for codepoint manipulation, so this alone is informational; weaponised use is also caught by the dedicated fromCharCode-stage and exploit-shape rules.
  • AcroForm button with action trigger low PDF_ACROFORM_BUTTON
    PDF contains a /Btn form field together with a SubmitForm/URI/Launch/JS trigger — this is the building block of fake 'Download' or 'Open' button overlays used in PDF phishing lures
  • Suspicious extracted artifact info 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.
  • 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.bitstream.com
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://ns.adobe.com/xap/1.0/
    • http://ns.adobe.com/pdf/1.3/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/xfa/promoted-desc/
    • http://ns.adobe.com/xdp/
    • http://www.xfa.org/schema/xci/2.6/
    • http://www.xfa.org/schema/xfa-template/2.6/
    • http://www.xfa.org/schema/xfa-locale-set/2.7/
    • http://www.xfa.org/schema/xfa-locale-set/2.6/
    • http://www.xfa.org/schema/xfa-form/2.8/
    • http://www.xfa.org/schema/xfa-data/1.0/

Extracted artifacts 9

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0029_000.js
80d7888ecf9ad9e4d03cd8cc6959f589c8f8783f37d48bb4d7dae53f6684c595		 pdf-javascript-stream PDF /JS object 29 at offset 0x1E2A 8603 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).
stream_002_off00000a8f.js
672d461752be4a970c8e9721164ce074d252b55d09d46cc09259d2ce4fc09f7f		 decompressed-pdf-stream PDF FlateDecoded stream at offset 0xA8F 1546 bytes
stream_003_off00000d4c.bin
29cf1edfedd4f27f3c450646c5dc2510e6bf9e63eee1cd436ac517a465a2e1bf		 decompressed-pdf-stream PDF FlateDecoded stream at offset 0xD4C 1650 bytes
stream_004_off000010bc.bin
0f910ffeec733940f6ba1ae41dc6770eab5d615c05bccc95197878b62c8dc45f		 decompressed-pdf-stream PDF FlateDecoded stream at offset 0x10BC 2928 bytes
stream_006_off00001651.bin
4a60a9864cdf7382475d51051a03fdc43b32c31eb508893ccfccece34957f9f1		 decompressed-pdf-stream PDF FlateDecoded stream at offset 0x1651 56 bytes
stream_007_off000016d9.bin
fe122a09d8a0444608fdc5a6f4981a2dbd469f5bbfacb4bdd327c28ccc343e13		 decompressed-pdf-stream PDF FlateDecoded stream at offset 0x16D9 149 bytes
deobfuscated.js
af0fd7cb9a1ac04bf959044aee39efdd310681527f8a03fadef3e1fcb15b2e01		 deobfuscated-js PDF JavaScript deobfuscation pass 3865287 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 4 eval/decoder/string-building token(s). Carved artifact contains 16 long base64-like blob(s).
font_00_cff_off00004aaf.bin
ea8f409c7366ed46eeb553aa7b404f04641f482ba88463fbe253da60be5787e5		 pdf-font-stream PDF embedded font (cff) at offset 0x4AAF 1138 bytes
font_01_sfnt_off000054a2.bin
e31f8c8507e52f29008d946a00becde9f839e34cb108985ce66167bf881adafa		 pdf-font-stream PDF embedded font (sfnt) at offset 0x54A2 8084 bytes

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