PDF malware analysis — malicious · a656b1fb42ddf52b

MALICIOUS

PDF

7.7 KB

MD5: f84991ef431ffaa2d0ec4bbbeae354d0 SHA-1: 1aece6cb1f09a947a215838a81ae99b54de9d850 SHA-256: a656b1fb42ddf52b2d874baf4ded36afd1d532439a4c14af8a6d377e2736c450

224 Risk Score

Malware Insights

MITRE ATT&CK

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

The sample is a PDF file that leverages the CVE-2007-5659 vulnerability to execute obfuscated JavaScript. This script acts as a dropper, indicated by the 'PDF_JS_OBFUSCATED_DROPPER' heuristic, and is designed to download and execute a second-stage payload. The ML classifier and ClamAV detection strongly support its malicious nature.

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-35902 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Exploit.Agent-35902
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` `3cf6a22459cda11e607fc9e0dc0c88d01a8425e26488ff87df38d855ceb4dccf`	pdf-javascript-stream	PDF /JS object 5 at offset 0x148	465 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` `8a4b5a496033ccf79c588f6c8f00c9a7064cb8d4dc4e64c6e9ec95ca79a258fa`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x19A1	1777 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` `64b79e1f511dbfbfae110489219f198da6165f7ce31e16215a35baef48468637`	deobfuscated-js	annotation-subject callee-key decoded JavaScript at offset 0x347	4673 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 4 eval/decoder/string-building token(s).
`deobfuscated.js` `be993749a0676bc2907378bd5b48555f233537f508b439adb99b8ff81977eaa5`	deobfuscated-js	PDF JavaScript deobfuscation pass	21003 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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