PDF malware analysis — malicious · 5b625e97b9274e65

MALICIOUS

PDF

13.6 KB Created: 2012-10-20 14:29:31 -05:00 Authoring application: AMRITAv3.06_R02-08-2012 (www.amrita-ebook.org (via pdfTeX-1.40.10)

MD5: 4ebc5e79c83ac745b5f665b9ba9deed3 SHA-1: 4d94dbed307cce54d4468cdac886435c1af932ef SHA-256: 5b625e97b9274e6594c205932632e4f09f355daaa1a3dab8b97ed72de53535a9

266 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 that utilizes eval() and String.fromCharCode(), indicative of exploit code. Critical heuristics like PDF_JS_EXPLOIT_CLUSTER and PDF_JS_EXPORT_LAUNCH_DROPPER confirm its malicious nature as a dropper. The JavaScript is designed to launch an embedded file, likely a second-stage payload, leveraging the PDF's scripting capabilities.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 10

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.
exportDataObject + nLaunch — embedded-file launch-on-open dropper critical PDF_JS_EXPORT_LAUNCH_DROPPER

PDF JavaScript calls exportDataObject() with nLaunch set, which extracts the document's embedded file and launches it in its default application. This is a launch-on-open dropper: the embedded file is the payload. No benign workflow auto-launches an extracted PDF attachment. (matched in decompressed stream)
eval() call high PDF_EVAL

eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
Generic recovered JavaScript exploit stage high PDF_GENERIC_STAGE_RECOVERY

Bounded static stage recovery exposed hidden JavaScript through generic transforms such as null-byte collapse, percent decoding, marker replacement, arithmetic character codes, fromCharCode, numeric arrays, numeric-array minus-key decoders, alphabet-index arrays, /Producer half-difference metadata arrays, hex literals, marker-stripped Base64 literals, custom 6-bit XOR table decoders, or repeated-marker hex carriers. This rule is emitted only when the recovered stage contains exploit-like Acrobat JavaScript or shellcode markers.
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.
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. (matched inside decoded stream)
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://localhost
- http://www.amrita-ebook.org/fnv

Extracted artifacts 5

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0004_000.js` `fb6d981c6d14867c7b8cd1c032cc9e32eb9de798c3a9a16b8478be28720b6dcb`	pdf-javascript-stream	PDF /JS object 4 at offset 0x10F	37882 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 4 eval/decoder/string-building token(s).
`generic_stage_recovery_000.js` `b67b1b7d7ae519b0cb0cb7cebd67cb7d1ed86ec19374ced52a72351af39debc3`	deobfuscated-js	generic stage recovery split-literal-normalize from JavaScript object 4 at offset 0x10F	37824 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 4 eval/decoder/string-building token(s).
`generic_stage_recovery_001.js` `3042aa916411dfe317a2efc8dd9293cbf4b73580fed03e00cac35d0b2e24eb78`	deobfuscated-js	generic stage recovery split-literal-normalize from combined JavaScript objects at offset 0x10F	37845 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 4 eval/decoder/string-building token(s).
`combined_document_js_000.js` `6806337a4b7aed555e112fc9a7587976770c46837a1b029f1f79eef09a7c2ff6`	deobfuscated-js	combined document JavaScript streams at offset 0x10F	37903 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 4 eval/decoder/string-building token(s).
`font_00_type1_off000027b6.bin` `e3b644e141d5b5e5871ec659f544ccb7e35da870f4ca81abefc50f717ac245db`	pdf-font-stream	PDF embedded font (type1) at offset 0x27B6	3102 bytes

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