PDF malware analysis — malicious · 6dff997b6cc40479

MALICIOUS

PDF

1.9 KB

MD5: 1059e19aed4039379699b7f2592a1cc0 SHA-1: 9851976cf9b839dab6283c8a2f442309d04b3c5b SHA-256: 6dff997b6cc4047960dc3cf7448d0aa7ba6f2423efd6cf7c914e94cbf402ca4c

358 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1059.007 JavaScript

The PDF contains embedded JavaScript that utilizes `eval()` and `unescape()` functions, indicative of exploit code. This script is designed to download a second-stage payload from the URL http://91.212.198.43/klin/l.php?i=16, as confirmed by the 'PDF JavaScript shellcode contains an embedded download URL' heuristic. The presence of the CVE-2009-4324 heuristic further supports the exploitation of a known vulnerability for client execution.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 11

media.newPlayer — CVE-2009-4324 critical CVE exact CVE_2009_4324

PDF JavaScript calls media.newPlayer — CVE-2009-4324 is a use-after-free in Adobe Reader's multimedia plugin triggered by media.newPlayer(). Actively exploited as a zero-day in December 2009. (identified after JavaScript deobfuscation)
PDF JavaScript exploit cluster critical PDF_JS_EXPLOIT_CLUSTER

PDF combines an executable JavaScript/action surface with exploit staging indicators such as eval/unescape/fromCharCode, XFA script content, or a related CVE pattern. Benign form JavaScript remains low-severity, but this correlated cluster is high-confidence malicious behavior.
ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV

ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
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)
PDF JavaScript shellcode contains an embedded download URL high PDF_JS_SHELLCODE_DOWNLOAD_URL

Decoded PDF JavaScript shellcode contains a hardcoded http(s) URL stored as little-endian %uXXXX Unicode escapes. Reader exploit shellcode embeds the second-stage fetch URL this way and pulls it down with a urlmon/URLDownloadToFile-style download-and-execute (commodity downloader behaviour rather than a specific Acrobat CVE).
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)
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.
Embedded URL info EMBEDDED_URL

One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.

URL http://91.212.198.43/klin/l.php?i=16

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj111611_000.js` `433d6141b5fc932a52d94051061c1f7566cbde37bb51ce636d76e20ed4ab2bf6`	pdf-javascript-stream	PDF /JS object 111611 at offset 0x6B4	297 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 3 eval/decoder/string-building token(s).
`legacy_pdfkit_stage_000.js` `d39531a62c2598dc9961af98ff15486e663433bb388f9cc53b16dbc1eee8c778`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x189	2433 bytes
Detection ClamAV: Js.Exploit.Shellcode-18 Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).

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