SID 1:34227

Rule Category

INDICATOR-OBFUSCATION -- Snort detected a system behavior that suggests the system has been affected by malware. That behavior is known as an Indicator of Compromise (IOC). The symptoms could be a wide range of behaviors, from a suspicious file name to an unusual use of a utility. Symptoms do not guarantee an infection; your network configuration may not be affected by malware, but showing indicators as a result of a normal function. This alert specifically refers to a method of disguising code, known as obfuscation. Obfuscation methods are used to perform innocent convenience tasks (for instance, Javascript used to condense Jquery scripts, or a compiler using obfuscation to protect the full code for NDA reasons), or it could be used to hide an attack.

Alert Message

INDICATOR-OBFUSCATION Multiple AV products evasion attempt

Rule Explanation

The Gzip file parser in AVG Anti-Virus 10.0.0.1190, Bitdefender 7.2, Command Antivirus 5.2.11.5, Emsisoft Anti-Malware 5.1.0.1, F-Secure Anti-Virus 9.0.16160.0, Fortinet Antivirus 4.2.254.0, Ikarus Virus Utilities T3 Command Line Scanner 1.1.97.0, Jiangmin Antivirus 13.0.900, K7 AntiVirus 9.77.3565, Kaspersky Anti-Virus 7.0.0.125, McAfee Anti-Virus Scanning Engine 5.400.0.1158, McAfee Gateway (formerly Webwasher) 2010.1C, NOD32 Antivirus 5795, Norman Antivirus 6.06.12, Rising Antivirus 22.83.00.03, Sophos Anti-Virus 4.61.0, AVEngine 20101.3.0.103 in Symantec Endpoint Protection 11, Trend Micro AntiVirus 9.120.0.1004, Trend Micro HouseCall 9.120.0.1004, and VBA32 3.12.14.2 allows remote attackers to bypass malware detection via a .tar.gz file with multiple compressed streams. NOTE: this may later be SPLIT into multiple CVEs if additional information is published showing that the error occurred independently in different Gzip parser implementations. Impact: CVSS base score 4.3 CVSS impact score 2.9 CVSS exploitability score 8.6 confidentialityImpact NONE integrityImpact PARTIAL availabilityImpact PARTIAL Details: Ease of Attack:

What To Look For

No information provided

Known Usage

No public information

False Positives

No known false positives

Contributors

Talos research team. This document was generated from data supplied by the national vulnerability database, a product of the national institute of standards and technology. For more information see [nvd].