RTF malware analysis — malicious · a5c5472dcd43da93

MALICIOUS

RTF

66.3 KB Authoring application: riched20 6.3.9600 First seen: 2018-03-24

MD5: 3cca313171ef1d2062b428fab378c860 SHA-1: 175fac7665101af4b940197e4c8296bc67d67f19 SHA-256: a5c5472dcd43da9341addc4e77631c330b89a831d902a8c4d06979171b2ab5ea

402 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains an embedded Equation Editor OLE object that exploits CVE-2017-11882. This exploit is designed to execute arbitrary code, and in this case, it likely downloads and executes a second-stage payload from the URL http://congratulations.ie/gdfonts/pa.exe. The presence of PE header in hex data and ClamAV detection further confirms its malicious nature.

Heuristics 10

Equation Editor CLSID critical CVE likely RTF_EQUATION_EDITOR

Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
CVE-2017-11882 — Equation Editor FONT record overflow critical CVE likely CVE_2017_11882

Equation Editor MTEF contains an overlong FONT typeface field, the vulnerable copy primitive for CVE-2017-11882. This is stronger evidence than the Equation Editor CLSID alone because it identifies the malformed record that drives code execution in EQNEDT32.EXE.
ClamAV: Rtf.Exploit.CVE_2017_11882-6584355-1 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Rtf.Exploit.CVE_2017_11882-6584355-1
Equation Editor object class critical RTF_OBJCLASS_EQUATION

Object class 'equation.3' references Equation Editor
PE header (with DOS stub) in hex data critical RTF_MZ_HEX

Hex-encoded PE (MZ + DOS stub) found inside RTF — likely an embedded executable payload
\objupdate forces OLE activation high RTF_OBJUPDATE

RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
OLE object data medium RTF_OBJDATA

RTF contains 1 \objdata section(s) — embedded OLE objects
Embedded OLE object medium RTF_OBJEMB

RTF contains \objemb — embedded OLE object
Suspicious extracted artifact medium 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://congratulations.ie/gdfonts/pa.exe In RTF body

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off000000fe.bin`	rtf-objdata-decoded	RTF \objdata at offset 0xFE	33458 bytes
SHA-256: `76490e5ded2b3164a525d40b1bc18cdccc9563509e53ce9ae0b2f77f8ac5a8f7`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis found candidate code region(s). Indicators: NOP sled

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