Malicious RTF — malware analysis report

Static analysis result for SHA-256 a274a0c70fa99631…

MALICIOUS

RTF

7.1 KB First seen: 2019-04-18
MD5: 5d7bbd2b77e8cf86e8e9d7658cf8821a SHA-1: 75ffefdbd755ae35915c6fb70bc60ebc36855429 SHA-256: a274a0c70fa996315bb6b8e81a1be9c2b37b89711ea0813fecb465fdcbbc26f0
260 Risk Score

Malware Insights

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

The RTF file contains an embedded OLE object that leverages a known vulnerability in Microsoft Equation Editor (CVE-2017-11882). This vulnerability allows for the execution of arbitrary code upon opening the document. The presence of the Equation Editor CLSID and the specific font record overflow pattern strongly indicate exploitation of this CVE. The file is classified as malicious due to this exploit.

Heuristics 6

  • 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: Doc.Exploit.CVE_2017_11882-6934206-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Exploit.CVE_2017_11882-6934206-0
  • \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 1 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000003b.bin rtf-objdata-decoded RTF \objdata at offset 0x3B 3625 bytes
SHA-256: 3ae54ef505490062ce2467c0edc909d2b1616814bb41bc5bec8fe1652cfb8068