PDF malware analysis — malicious · 35fd845364be53da

MALICIOUS

PDF

25.1 KB Created: 2011-72-51 03:25:00 Authoring application: String.fromCharCode

MD5: e18568a6bc2997bcd5061d5be021f69a SHA-1: 6a18d0408bd5e0c646235ee9655b53c20c120122 SHA-256: 35fd845364be53da762ab4be4c50171d66d0abedc555bf72bd06a52b5f2dd088

378 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.001 Malicious Link T1204.002 Malicious File

This PDF file is identified as malicious due to multiple critical heuristic firings indicating exploitation of CVE-2009-4324, CVE-2009-0927, CVE-2007-5659, and CVE-2008-2992. The embedded JavaScript, recovered as 'info_arithmetic_stage_000.js', acts as a stager that decodes and evaluates further JavaScript, a common technique for downloading and executing additional malicious content. The use of String.fromCharCode and arithmetic operations within the PDF metadata to construct JavaScript is a known obfuscation method.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 10

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)
Collab.getIcon — CVE-2009-0927 critical CVE exact CVE_2009_0927

PDF JavaScript calls Collab.getIcon — CVE-2009-0927 is a stack buffer overflow in Adobe Reader triggered by Collab.getIcon() with a crafted argument. Allows arbitrary code execution. (identified after JavaScript deobfuscation)
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)
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 metadata arithmetic JavaScript stager high PDF_INFO_ARITHMETIC_JS_STAGER

PDF metadata hides JavaScript as arithmetic character-code tokens inside document information fields, then a launcher rebuilds it with String.fromCharCode and eval. The decoder is gated on metadata access from the launcher, a large arithmetic token table, and recovered exploit-like JavaScript.
PDF metadata JavaScript eval stager high PDF_METADATA_EVAL_STAGER

PDF JavaScript reads document metadata fields such as title, subject, or producer, decodes character data with parseInt/String.fromCharCode style helpers, and evals the recovered stage. This is a high-signal exploit-kit staging pattern.
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.
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 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0001_000.js` `a64f1b019a9f9047ffa0a0df5e4e77ea5f5960c7031a3a3e5f1f9a91b4e60b87`	pdf-javascript-stream	PDF /JS object 1 at offset 0x6194	525 bytes
`info_arithmetic_stage_000.js` `387814f6435facf12482d232a0ec34d5bf94fb64fe12925b9acd1b5bb7ab105d`	deobfuscated-js	PDF /Info Title arithmetic JavaScript at offset 0x23	3636 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 11 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).

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