PDF malware analysis — malicious · ff45610c13122e2c

MALICIOUS

PDF

7.8 KB

MD5: fd94e3b25a1df19f9e6913b0b16d21f8 SHA-1: 8251c56a5ed41d3d8c5f4d89d610a0973330bb67 SHA-256: ff45610c13122e2c10259b9dc49fa877b5153251ab1c824236d2fc7a7c9c0177

164 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 JavaScript/JScript T1204.001 Malicious Link/Document

The PDF file contains obfuscated JavaScript that leverages the CVE-2007-5659 vulnerability. The JavaScript is designed as a multi-stage dropper, indicated by the 'PDF_JS_OBFUSCATED_DROPPER' heuristic. It decodes a hex-dashed payload and uses `String.fromCharCode` to reconstruct and execute further stages, ultimately leading to the download and execution of a second-stage payload. The ML classifier strongly indicates maliciousness.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 7

Collab.collectEmailInfo — CVE-2007-5659 critical CVE exact CVE_2007_5659

PDF JavaScript calls Collab.collectEmailInfo — CVE-2007-5659 is a buffer overflow in Adobe Reader triggered by a long argument or heap-sprayed message field passed to Collab.collectEmailInfo(). Part of a series of Acrobat JS API exploits. (identified after JavaScript deobfuscation)
Obfuscated multi-stage PDF JavaScript dropper high PDF_JS_OBFUSCATED_DROPPER

PDF JavaScript shows 4 independent signals of exploit-kit-style multi-stage obfuscation: annot_subject_stage, hex_codec_loop, hex_dashed_payload, incremental_eval_build. This is strongly consistent with pre-2011 Adobe Reader PDF droppers — OpenAction JS reads encoded data from annotation subjects, decodes it through one or more hex / base-N loops, and invokes eval indirectly (method name built one character at a time). The actual CVE is hidden in the final decoded layer and is not visible via static analysis.
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)
syncAnnotScan annotation-staging primitive low PDF_FOXIT_SYNCANNOTSCAN

PDF JavaScript calls syncAnnotScan() — a no-op annotation-enumeration primitive used by exploit-kit JavaScript to stage payload reads from annotation /Subject fields before eval(). Not a vulnerable sink itself; rarely seen in legitimate PDFs. (matched in decompressed stream)
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.

Extracted artifacts 4

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0005_000.js` `852cce793efb6da930945a67e484cbb58255ac23ba75b9acf4900b180bb1bd7b`	pdf-javascript-stream	PDF /JS object 5 at offset 0x148	503 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).
`legacy_pdfkit_stage_000.js` `837fd792bd5f689e1c30f77d31cf60f2d30a58d9f2ddf0c8bfaed906910d2096`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1A12	1694 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`legacy_pdfkit_stage_001.js` `d7b9ab9417a172b6cacf652dce90a7c20e87781857c66df1fbde1e48774ffa42`	deobfuscated-js	annotation-subject callee-key decoded JavaScript at offset 0x352	4824 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 4 eval/decoder/string-building token(s).
`deobfuscated.js` `9b760a4074792ced0962d0b0ece6ca52aff7c6efaf609bcb4db4e3592871b3f1`	deobfuscated-js	PDF JavaScript deobfuscation pass	25026 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 7 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).

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