PDF / .TXT malware analysis — malicious · d5cbb285447f84af

MALICIOUS

PDF / .TXT

15.6 KB

MD5: cc354df31e74ae0abce9fc096cb1f9d5 SHA-1: 44cb93c85ff6659170443d90a3f2004b1afc7a04 SHA-256: d5cbb285447f84af5d6e8f7b1fd63a82f9fed57ed93225a0508f8c4d6d3d2494

194 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 JavaScript/JScript T1204.002 Malicious File

The PDF file contains heavily obfuscated JavaScript, indicated by multiple heuristic firings including 'PDF_JS_OBFUSCATED_DROPPER' and 'PDF_FROMCHARCODE'. The deobfuscation process revealed JavaScript capable of exploiting CVE-2007-5659 via the Collab.collectEmailInfo method. This script is designed to download and execute a second-stage payload, as suggested by the 'PDF_JS_OBFUSCATED_DROPPER' heuristic and the presence of multiple deobfuscated JavaScript files. The ClamAV detection further confirms its malicious nature.

Heuristics 8

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 static deobfuscation)
ClamAV: Pdf.Exploit.Agent-35901 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Exploit.Agent-35901
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 4

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0005_000.js` `4718a27c2224fc36bf24f8e8e04598f1ad78adce4401c7be2708318738a6983d`	pdf-javascript-stream	PDF /JS object 5 at offset 0x148	469 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` `8092221e854d4f4ab883844d2b9f0d8b7e9540f9fb22e58c8d7c6510d3539fda`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1B15	11544 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).
`deobfuscated.js` `cc9987316e56b123c3930e3a32e98d4dadc5f9a373f99cb1ff38e7cf9ade6615`	deobfuscated-js	PDF JavaScript deobfuscation pass	78000 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 10 eval/decoder/string-building token(s). Carved artifact contains 2 long base64-like blob(s).
`legacy_base21_stage_000.js` `65769eeb40fdbb5d80793f20e00d9f407f71538cac7a98bfec5937801c84f9d2`	deobfuscated-js	PDF JavaScript deobfuscation pass, legacy base-21 pair decoder	4990 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).

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