PDF malware analysis — malicious · c61cbdcb83542e3d

MALICIOUS

PDF

45.7 KB

MD5: aceea3460fb7ce0af393ba3a4b4345c0 SHA-1: 7f6433b6c5045fd127fb9cc06cac427fd151805f SHA-256: c61cbdcb83542e3d8c522da7e5ffe3d3b68ff771a095a2d8a31901bf33c44f59

286 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1059.007 JavaScript T1566.001 Spearphishing Attachment

The PDF file contains embedded JavaScript that leverages the CVE-2010-2883 exploit. The script attempts to download and execute a second-stage payload, indicated by the 'generic_stage_recovery' artifacts. The presence of the exploit cluster and ML classification strongly suggests malicious intent.

Machine Learning

Nyx PDF Classifier malicious score 0.9995

Heuristics 11

Adobe Reader CoolType SING font exploit — CVE-2010-2883 critical CVE likely CVE_2010_2883

PDF embeds a TrueType/OpenType font with an actual SING table and pairs it with JavaScript heap-spray shellcode. This matches the public Adobe Reader CoolType SING exploit shape for CVE-2010-2883.
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.
unescape() call high PDF_UNESCAPE

unescape() found — often used to decode shellcode in PDF JS exploits (matched inside decoded stream)
Generic recovered JavaScript exploit stage high PDF_GENERIC_STAGE_RECOVERY

Bounded static stage recovery exposed hidden JavaScript through generic transforms such as null-byte collapse, percent decoding, marker replacement, arithmetic character codes, fromCharCode, numeric arrays, numeric-array minus-key decoders, alphabet-index arrays, /Producer half-difference metadata arrays, hex literals, marker-stripped Base64 literals, custom 6-bit XOR table decoders, or repeated-marker hex carriers. This rule is emitted only when the recovered stage contains exploit-like Acrobat JavaScript or shellcode markers.
Embedded script payload in PDF stream medium PDF_EMBEDDED_SCRIPT_PAYLOAD

PDF stream bytes contain an HTML/XFA <script> tag without accompanying Windows shell-execution primitives — common in accessible XFA forms but worth surfacing for analyst review.
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.
XFA form low PDF_XFA

PDF uses XML Forms Architecture — can contain script logic
AcroForm button with action trigger low PDF_ACROFORM_BUTTON

PDF contains a /Btn form field together with a SubmitForm/URI/Launch/JS trigger — this is the building block of fake 'Download' or 'Open' button overlays used in PDF phishing lures
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://www.bitstream.com
- http://ns.adobe.com/xdp/
- http://www.xfa.org/schema/xci/3.0/
- http://www.xfa.org/schema/xfa-template/3.0/
- http://www.xfa.org/schema/xfa-data/1.0/

Extracted artifacts 7

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0001_000.js` `f8e3c9c42b5b750538c7c1a7be13f0a76a063e199fa715fca7db2d00053cbad5`	pdf-javascript-stream	PDF /JS object 1 at offset 0xA	2837 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).
`stream_002_off0000ad98.js` `d1dfd457a2fdd3cec4091f689f39b85b35666aa5599ef3a8d5f9a80d1e2ce105`	decompressed-pdf-stream	PDF FlateDecoded stream at offset 0xAD98	1042 bytes
`generic_stage_recovery_000.js` `c13f4c376f86825373ae1ea695d8e6e6657da8dce01866bfffd18c01c1bc8650`	deobfuscated-js	generic stage recovery split-literal-normalize from JavaScript object 1 at offset 0xA	2787 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).
`generic_stage_recovery_001.js` `14ba9a00dc53f9485fe4be67fdb93a2f15f6f894037b0ab065602cdc1f5ecc05`	deobfuscated-js	generic stage recovery split-literal-normalize from decompressed stream at 0x0 at offset 0x0	46745 bytes
`font_00_sfnt_off00000fdc.bin` `edb230aee2530de721b12a447ced8ecd5381b80726cbfddbf8d98efa62145c2c`	pdf-font-stream	PDF embedded font (sfnt) at offset 0xFDC	65932 bytes
`font_01_type1_off0000b239.bin` `c6bf78478c9c4dd5b3b86554d34c78f847f70af4118f9ff083c1fccf0e8e932b`	pdf-font-stream	PDF embedded font (type1) at offset 0xB239	97 bytes
`font_02_type1_off0000b4c1.bin` `b749644b3e758e7335900ab2e7499eaa64b3a946849f1f8a0948287bdd96763d`	pdf-font-stream	PDF embedded font (type1) at offset 0xB4C1	144 bytes

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