RTF malware analysis — malicious · 86be98c5baa52cf4

MALICIOUS

RTF

1.62 MB First seen: 2020-09-15

MD5: b9122ac4b19be3138d09639cbbd68620 SHA-1: 77b56aadcb5a94f9739fb681c5d135108f7b61ba SHA-256: 86be98c5baa52cf4df40a61ef4dba40a30fcbfb72b9bf1159440ca88ef382252

240 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution

The RTF document contains an embedded OLE object that exploits CVE-2017-11882 through the Equation Editor. This exploit is designed to execute a Visual Basic script, which in turn attempts to run 'svchost.exe' with suspicious arguments. The script also references a local file path 'C:\fakepath\mguay.vbs', indicating a potential dropper or downloader functionality.

Heuristics 6

Obfuscated Equation Editor ProgID + activation critical CVE related RTF_EQUATION_EDITOR

RTF decodes to an Equation.3 ProgID from top-level \objdata hex after nested RTF junk groups are ignored, and the document also contains \objemb plus \objupdate activation. This is an obfuscated Equation Editor exploit surface associated with CVE-2017-11882 / CVE-2018-0802 families, but no exact malformed MTEF CVE primitive was recovered from this object.
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.
\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.
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 3 \objdata section(s) — embedded OLE objects
Embedded OLE object medium RTF_OBJEMB

RTF contains \objemb — embedded OLE object

Extracted artifacts 3

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off00000cdc.bin`	rtf-objdata-decoded	RTF \objdata at offset 0xCDC	7838 bytes
SHA-256: `368852947b1ce464aa66678ddf8dcdfaaef7d10e357fd188b9240162f4f8acae`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): WScript.CreateObject("WScript.Shell"), WScript.StdOut.WriteLine objExecObject.StdOut.ReadLine(
`objdata_01_off00005533.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x5533	126 bytes
SHA-256: `a1e4d55798eef693c178bcba7ac5c1c1e686adba0af5d95035cc5964d7e27f02`
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 shell/COM execution token(s).
`objdata_02_off00006528.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x6528	482391 bytes
SHA-256: `30e70399d828f5d9b6b322511703df288d4e1c9ac71bf168924275a7dd93f7d9`

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