PDF malware analysis — malicious · fb5d28d0b966228b

MALICIOUS

PDF

8.2 KB

MD5: 5c408b0a18a5bd3dd813726c21cb2f23 SHA-1: 486145b5c1bef6dd5fbfc7ff1d9b87c7c9b34387 SHA-256: fb5d28d0b966228ba4baf7e4a4a368c03bd7d5de509e55026f42ad378e12d665

134 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

The PDF contains obfuscated JavaScript, identified as a multi-stage dropper. This script is designed to decode and execute further stages, ultimately leading to the download and execution of a second-stage payload. The ClamAV detection 'Pdf.Exploit.Agent-35902' further confirms its malicious nature. The primary attack vector involves exploiting PDF vulnerabilities to achieve arbitrary code execution.

Heuristics 7

ClamAV: Pdf.Exploit.Agent-35902 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Exploit.Agent-35902
Obfuscated multi-stage PDF JavaScript dropper high PDF_JS_OBFUSCATED_DROPPER

PDF JavaScript shows 5 independent signals of exploit-kit-style multi-stage obfuscation: annot_subject_stage, hex_codec_loop, hex_dashed_payload, 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 3

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0005_000.js` `3cf6a22459cda11e607fc9e0dc0c88d01a8425e26488ff87df38d855ceb4dccf`	pdf-javascript-stream	PDF /JS object 5 at offset 0x148	465 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`legacy_pdfkit_stage_000.js` `04355c06fa71cdd9c5e073af497fa65aa99c59b13845f313090b7bdaf7e41b70`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1BA8	1785 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`deobfuscated.js` `01e2c6f2eda99ca95f083406d14c91d42c91c2405b0e174373adc7066b7af2d9`	deobfuscated-js	PDF JavaScript deobfuscation pass	24821 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).

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