PDF malware analysis — malicious · 3ba71089e0ba3bcb

MALICIOUS

PDF

8.2 KB

MD5: c73f0b6baac2f195452ad84139332d7b SHA-1: a03ddfad00ae19ea6bf06001bde73a2e9adcdd3d SHA-256: 3ba71089e0ba3bcb65ff54014ad1b7afa2dc6b3b05c491c833e4d61f292e839d

224 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.001 Malicious Link T1071.001 Web Protocols T1204.002 Malicious File

The PDF exploits CVE-2007-5659 by leveraging JavaScript embedded within annotations. The heuristic 'PDF_JS_OBFUSCATED_DROPPER' indicates a multi-stage dropper that decodes and executes JavaScript. This script is responsible for downloading and executing a second-stage payload, as evidenced by the 'ML_NYX_PDF_MALICIOUS' and 'CLAMAV_DETECTION' firings. The obfuscated nature of the script and the use of 'String.fromCharCode' with hex decoding suggest a deliberate attempt to evade detection.

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` `9045036eed334a24ea1804fabbcc6463228a970ccfc668be5eab5c023aa9a5ac`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1BD2	1732 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` `3e312f5d7df11647a8974ee10ecf0bd982c4337ac3e6264a0f6889b304fb420e`	deobfuscated-js	annotation-subject callee-key decoded JavaScript at offset 0x347	5171 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).
`deobfuscated.js` `86cc72ce6eb48115fc382f965ba74faa051633a89029ac427d897ee4824e0010`	deobfuscated-js	PDF JavaScript deobfuscation pass	26559 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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