Rule Category

FILE-OTHER -- Snort detected traffic targeting vulnerabilities in a file type that does not require enough rule coverage to have its own category.

Alert Message

FILE-OTHER libexpat internal entity heap over-read attempt

Rule Explanation

This event is generated when an attempt to cause a heap over-read is performed against Expat application or application utilizing the libexpat library. Impact: Remote Code Execution Details: Libexpat is vulnerable to a heap over-read caused by a malicious XML DTD entity. The malicious entity attempts to trick the parser into thinking the entity was closed so when the application tries to parse the contents as if it was part of the XML document body it is actually performing a heap over-read. Ease of Attack: Simple

What To Look For

Known Usage

No public information

False Positives

No known false positives

Contributors

Cisco Talos Intelligence Group

MITRE ATT&CK Framework

Tactic:

Technique:

For reference, see the MITRE ATT&CK vulnerability types here: https://attack.mitre.org

CVE

Rule Vulnerability

CVE Additional Information

CVE-2019-15903
In libexpat before 2.2.8, crafted XML input could fool the parser into changing from DTD parsing to document parsing too early; a consecutive call to XML_GetCurrentLineNumber (or XML_GetCurrentColumnNumber) then resulted in a heap-based buffer over-read.
Details
Severity Base Score7.5
Impact Score3.6 Exploit Score3.9
Confidentiality ImpactNONE Integrity ImpactNONE
Availability ImpactHIGH Attack VectorNETWORK
ScopeUNCHANGED User InteractionNONE
Authentication Ease of AccessLOW
Privileges RequiredNONE