PDF malware analysis — malicious · 7401e57bdf2ad85f

MALICIOUS

PDF

4.1 KB

MD5: f9bdb5494ee0bb7b3c54dead12c50b84 SHA-1: 3498f704694c76ead6a07bb0bb5979f4971daea6 SHA-256: 7401e57bdf2ad85f924115f48f3e28386161ef802937afc2277fd711d06e622d

258 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1059.007 JavaScript

This PDF file contains embedded JavaScript that exploits CVE-2008-2992, a known vulnerability in Adobe Reader. The script decodes and evaluates obfuscated JavaScript, which in turn downloads a second-stage payload from the URL http://91.121.2.103/~nejejida/u/load.php. The use of eval() and String.fromCharCode() indicates a malicious intent to execute arbitrary code.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 9

util.printf — CVE-2008-2992 critical CVE exact CVE_2008_2992

PDF JavaScript calls util.printf() — CVE-2008-2992 is a stack buffer overflow in Adobe Reader triggered by a long format-specifier argument. Widely exploited in the wild after disclosure. (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.
eval() call high PDF_EVAL

eval() found — commonly used for obfuscated exploit execution (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://91.121.2.103/~nejejida/u/load.php

Extracted artifacts 3

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0013_001.js` `fa931209893793550dfbe1a44c2979e3452015767fed3043d9809f2f98eaa0f0`	pdf-javascript-stream	PDF /JS object 13 at offset 0x368	6401 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).
`acroform_b64_00.js` `75d5b64979542d727aec3bcf701310552be87c2b69b90402fe019cfdf0b3fe09`	deobfuscated-js	PDF AcroForm base64 (decompressed) at offset 0x99D	3646 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).
`custom_b64_stage_000.js` `630271bdf2c0746307e9b69346e625b522f9354e39551acc9631e043386ed8c5`	deobfuscated-js	custom Base64 decoded JavaScript layer 2 (PDF /JS object 13) at offset 0x95E	2025 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).

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