PDF malware analysis — malicious · 41bb76c6c049bec8

MALICIOUS

PDF

7.8 KB

MD5: bbc940782c1f9f2757e1bf6c7ff6d51b SHA-1: b3f58450e08ba20db4dc94fc70eabe80401796fd SHA-256: 41bb76c6c049bec8714d8cfeeb268d7d2647c21758305665772a372de1f0c415

164 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.001 User Execution: Malicious Link T1071.001 Web Protocols: HTTP

This PDF file exploits CVE-2007-5659 via embedded JavaScript. The JavaScript is heavily obfuscated and appears to be a multi-stage dropper. The primary function of the script is to decode and execute further stages, ultimately leading to the download and execution of a malicious payload. The ML classifier strongly indicates malicious intent.

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` `bbdac66082bd0ad4e434271289b5579745ad12002350c2b9557eac12a4faba7e`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1A74	1619 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` `87905844f571db4771c31505d6fe439849a1b3e0dadbe6ae426b8edda32f06a0`	deobfuscated-js	annotation-subject callee-key decoded JavaScript at offset 0x352	4846 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 4 eval/decoder/string-building token(s).
`deobfuscated.js` `0b5de05cee83ee8bf21b7b84fad798e3c1448055abf0e7f8ab2ddf096d9af619`	deobfuscated-js	PDF JavaScript deobfuscation pass	24342 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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