PDF malware analysis — malicious · 98a8b5559cbd9d0f

MALICIOUS

PDF

8.3 KB

MD5: ab6b4a98c14f2ebbe6af8d6e841b44c3 SHA-1: f24d22ca978aaac30b9fc5900c412c3b3bda19ef SHA-256: 98a8b5559cbd9d0f7fcf4b20000fe16f5c88f6fc67746a87467d3c7e24f2aa34

124 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.001 Malicious Link

The PDF file contains embedded JavaScript that is heavily obfuscated using String.fromCharCode and other techniques. Heuristics indicate the exploitation of CVE-2007-5659 via the `Collab.collectEmailInfo` method. The primary function of the embedded script appears to be the download and execution of a secondary payload, as suggested by the ML classifier and the presence of multiple deobfuscated JavaScript stages. The exact nature of the second-stage payload is not discernible from the provided evidence.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 6

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)
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. (identified after JavaScript deobfuscation)
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_obj0004_000.js` `be4694a17eb89a55f7eb3db389ba2bc4f102f4c7dcfc99549d848cdb7df5dfb5`	pdf-javascript-stream	PDF /JS object 4 at offset 0xE1	1940 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`numeric_charcode_stage_000.js` `6c41320119e160dc719997b9a2efb3600ea9d7e9d7e44b4dc2125762dc9f365f`	deobfuscated-js	numeric char-code string decoded JavaScript at offset 0xEF	505 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` `5cac0ec22d63e47f789ea14600ca6d1d00a354aa70dc7b6726e34d9b0b4e7c48`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1BA8	1798 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` `deb1d88f551c091455022f117d94ff8a1c4728bc2854fd04a3d5677e80b3431e`	deobfuscated-js	annotation-subject callee-key decoded JavaScript at offset 0x4C3	4916 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).

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