PDF malware analysis — malicious · 851d29bdf6637953

MALICIOUS

PDF

17.4 KB

MD5: f3f657837efc3b9d3dde75e7cb22c909 SHA-1: 3b86f1b544f7e3aed5fcb8cb852330bdeac9073a SHA-256: 851d29bdf663795374e8e9516d0b08f7a4a8ac1fb8f8dcde519bec9cd673c354

234 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 JavaScript T1204.002 Malicious Link

The PDF document contains obfuscated JavaScript, identified as a multi-stage dropper. This script leverages the CVE-2007-5659 vulnerability (Collab.collectEmailInfo) to execute its payload. The dropper's primary function is to download and execute a second-stage payload from a remote source, indicated by the 'Obfuscated multi-stage PDF JavaScript dropper' heuristic. The extensive obfuscation and multi-stage nature suggest a sophisticated downloader designed to evade detection.

Heuristics 9

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-35901 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Exploit.Agent-35901
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.
Obfuscated multi-stage PDF JavaScript dropper high PDF_JS_OBFUSCATED_DROPPER

PDF JavaScript shows 4 independent signals of exploit-kit-style multi-stage obfuscation: annot_subject_stage, hex_codec_loop, 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_obj0009_000.js` `4718a27c2224fc36bf24f8e8e04598f1ad78adce4401c7be2708318738a6983d`	pdf-javascript-stream	PDF /JS object 9 at offset 0x4311	469 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`annotation_subject_callee_hex_stage_000.js` `79d4fb048edde04d6bca3b82b43b45892b5cc633101f1c088222388fae63f223`	deobfuscated-js	annotation-subject callee-key decoded JavaScript at offset 0x1A9C	5320 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).
`legacy_pdfkit_stage_000.js` `78439f5f34270ea9fab8b5e38f41f61e6b01c05f7c9980908b5e456b38757d32`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1AF0	12033 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` `e78f203cb62e8f32930793718d49656173281a452854f2d0ec137487b58bbf96`	deobfuscated-js	PDF JavaScript deobfuscation pass	99224 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 6 eval/decoder/string-building token(s). Carved artifact contains 3 long base64-like blob(s).

Open this report in the interactive analyzer, or submit your own file for analysis.