Malicious RTF — malware analysis report

Static analysis result for SHA-256 858cc2521558e72b…

MALICIOUS

RTF

1.58 MB Created: 2018-05-20 22:10:00 First seen: 2018-07-27
MD5: 773817cbe63dabd02d54d92efbb91c06 SHA-1: 228f2c0e6afcc688a85fc83fcb8abfd85f4be7ed SHA-256: 858cc2521558e72b7724004f84f3ca64357233a0552efd24cd13e0ecb22786d8
242 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains embedded OLE objects and triggers critical heuristics for CVE-2017-11882 (Equation Editor) and CVE-2017-8759 (MSXML SAX OLE activation). These vulnerabilities are commonly exploited to execute arbitrary code. The presence of an unknown URL suggests the file attempts to download and execute a second-stage payload, likely an MSI installer.

Heuristics 7

  • 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.
  • CVE-2017-8759 — MSXML SAX OLE activation critical CVE likely CVE_2017_8759
    RTF contains a hex-encoded OLE1 object for Msxml2.SAXXMLReader.6.0 followed by an embedded OLE compound document, and the document requests OLE activation. This matches the RTF staging shape used for CVE-2017-8759 SOAP/WSDL parser code injection.
  • \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.
  • Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX
    RTF contains ~1196KB of hex-encoded data inside \objdata sections — may hide a payload
  • 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://inova-tech.net/x1/skmb092775.msi In RTF body
    • http://schemas.microsoft.com/office/word/2003/wordmlIn RTF body
    • http://schemas.openxmlformats.org/drawingml/2006/mainIn RTF body

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000035bc.bin rtf-objdata-decoded RTF \objdata at offset 0x35BC 33326 bytes
SHA-256: 4b550e51ee1de480a302a6670403a81549b540a53f4f5434afdd37f7f2dc940a
objdata_01_off00130cac.bin rtf-objdata-decoded RTF \objdata at offset 0x130CAC 15672 bytes
SHA-256: 1002bf491a07d2ba83229cd814278aff7ab1c4b51d1217310830a51a1b3fa865

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