PDF malware analysis — malicious · b6a38a9a899392d5

MALICIOUS

PDF

7.9 KB

MD5: b2c0a35ae01ce49b6f47e53c3e97925a SHA-1: 71a6f3aa3e877c49495f11a2a6dfcf2025e2b0a1 SHA-256: b6a38a9a899392d51a4e3a9d9334cf7be5b86349a51ac8b94e397c34dcc57e09

224 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.001 Malicious Link T1071.001 Web Protocols

The PDF document contains obfuscated JavaScript, identified by the 'PDF_JS_OBFUSCATED_DROPPER' heuristic, which exploits CVE-2007-5659. This script is designed to download and execute a second-stage payload. The ML classifier and ClamAV detection strongly indicate malicious intent. The presence of multiple deobfuscated JavaScript files further supports the multi-stage nature of the attack.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 8

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)
ClamAV: Pdf.Exploit.Agent-35901 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Exploit.Agent-35901
Obfuscated multi-stage PDF JavaScript dropper high PDF_JS_OBFUSCATED_DROPPER

PDF JavaScript shows 5 independent signals of exploit-kit-style multi-stage obfuscation: annot_subject_stage, hex_codec_loop, hex_dashed_payload, incremental_eval_build, repeated_pluginschk. 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` `4718a27c2224fc36bf24f8e8e04598f1ad78adce4401c7be2708318738a6983d`	pdf-javascript-stream	PDF /JS object 5 at offset 0x148	469 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`legacy_pdfkit_stage_000.js` `4d862ccf5b5b8ef7e83e1160f477128d32938d201cf1a77dbab8d103d46f4948`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1A9D	1758 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` `a82247229e4990fc8b4b0bf946b70f1731ecb5a65d4f3e1817becb6b2f611ca0`	deobfuscated-js	annotation-subject callee-key decoded JavaScript at offset 0x34B	4900 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).
`deobfuscated.js` `74f159b7ccd42cfc44f833e54cfab135ee976e90458fe1c6559ff37dabde5f17`	deobfuscated-js	PDF JavaScript deobfuscation pass	42617 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).

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