PDF malware analysis — malicious · 981a7462f171cabf

MALICIOUS

PDF

9.1 KB

MD5: 462d4e9840f2f1824c65be9eea51d3cd SHA-1: 63cf28d8354110dd1232c0cb563d25ee7f1b4f38 SHA-256: 981a7462f171cabffbde643c7cd1a842199216f6847ceadb36734f8fad76d154

356 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.001 Malicious Link

The PDF document contains heavily obfuscated JavaScript, indicated by multiple heuristic firings including PDF_EVAL, PDF_UNESCAPE, and PDF_ANNOT_SUBJECT_MARKER_EVAL_STAGER. The critical CVE-2007-5659 firing points to the use of the Collab.collectEmailInfo method to launch this JavaScript. The script's primary function appears to be downloading and executing a second-stage payload, as suggested by the large size of the deobfuscated JavaScript and the presence of multiple embedded JavaScript streams. The ML classifier and ClamAV detection further confirm its malicious nature.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 10

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)
Annotation subject percent-decoding eval stager critical PDF_ANNOT_SUBJECT_MARKER_EVAL_STAGER

OpenAction JavaScript forces annotation enumeration, reads an annotation /Subject payload with getAnnots(), rewrites marker bytes into percent escapes, decodes it with unescape(), and dispatches it through eval. This is a high-confidence exploit-kit staging pattern. It is intentionally not mapped to CVE-2009-1492 unless getAnnots() itself carries the crafted integer or long argument shape for that vulnerability.
ClamAV: Pdf.Exploit.Agent-35912 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Exploit.Agent-35912
eval() call high PDF_EVAL

eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
unescape() call high PDF_UNESCAPE

unescape() found — often used to decode shellcode in PDF JS exploits (matched inside decoded stream)
Annotation subject callee-key hex JavaScript stager high PDF_ANNOT_SUBJECT_CALLEE_HEX_STAGER

PDF JavaScript uses syncAnnotScan()/getAnnots() to read an indirect annotation /Subject stream, percent-decodes it through marker replacement, then uses a callee.toString()-derived key to decode and eval the final exploit stage.
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.
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_obj0007_000.js` `7218a1c68060953321573daa035b16f5f32928ce25a9eb656690dbe78cd9464e`	pdf-javascript-stream	PDF /JS object 7 at offset 0x19B	201 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).
`annotation_subject_callee_hex_stage_000.js` `7f93c17ac12006833a23f676ca8e1b1f6f610eb1db0b8fb9d023fa1823517030`	deobfuscated-js	annotation-subject callee-key decoded JavaScript at offset 0x14A	4909 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).
`legacy_pdfkit_stage_001.js` `d654c875eedd07ecb07463e877676b33c7f828eaf07f59d3e16693344abc57ca`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x2B5	11608 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).
`deobfuscated.js` `2198b9e6e2995dd8bf6bae41eb916301899784d50ec3a81c730cb0561a5c7ccb`	deobfuscated-js	PDF JavaScript deobfuscation pass	42694 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 4 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).

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