Source: cve@mitre.org
Exiv2 0.26 has a Null Pointer Dereference in the Exiv2::DataValue::toLong function in value.cpp, related to crafted metadata in a TIFF file.
Exiv2 0.26 is vulnerable to a Null Pointer Dereference when processing specially crafted TIFF image files. This flaw allows attackers to cause a denial-of-service (DoS) by crashing the application or potentially achieve remote code execution (RCE) under specific circumstances, impacting systems that use Exiv2 for image metadata handling.
Step 1: Payload Delivery: The attacker crafts a malicious TIFF image file containing specifically crafted metadata.
Step 2: File Ingestion: The victim application or system, which uses Exiv2 0.26, attempts to process the malicious TIFF file.
Step 3: Metadata Parsing: Exiv2's parsing routines begin to read the TIFF file's metadata.
Step 4: Vulnerability Trigger: The Exiv2::DataValue::toLong function is called to convert a malformed metadata value.
Step 5: Null Pointer Dereference: The function attempts to dereference a null pointer, leading to a crash and denial-of-service (DoS).
The vulnerability lies within the Exiv2::DataValue::toLong function in value.cpp of Exiv2 0.26. This function is responsible for converting metadata values to a long integer format. The flaw arises when handling crafted metadata within a TIFF file. Specifically, the code fails to properly validate a pointer before dereferencing it. When the function encounters a malformed or unexpected data structure within the TIFF file's metadata, it attempts to access memory through a null pointer, leading to a crash. This is a Null Pointer Dereference vulnerability. While the immediate impact is a DoS, depending on the context of how Exiv2 is used (e.g., as part of a web application or image processing pipeline), it could potentially be leveraged for RCE if the attacker can control the data being processed and the application's memory layout.
While no specific APT groups are definitively linked to exploiting CVE-2017-18005, the widespread use of Exiv2 in various applications and systems makes it an attractive target. This vulnerability could be incorporated into a larger exploit chain. CISA KEV: Not Listed.
Monitor for crashes or unexpected behavior in applications that use Exiv2, especially when processing TIFF files from untrusted sources.
Analyze crash dumps or core files for evidence of a null pointer dereference within the Exiv2::DataValue::toLong function.
Implement file integrity monitoring to detect changes to Exiv2 binaries or related libraries.
Network monitoring for unusual file transfers or HTTP requests involving TIFF files, especially if originating from suspicious IP addresses or user agents.
Examine system logs for error messages related to Exiv2 or image processing failures.
Upgrade to a patched version of Exiv2 (e.g., 0.27 or later).
Implement input validation to restrict the types and sizes of image files that are processed.
Isolate systems that process untrusted image files to limit the blast radius of a potential exploit.
Apply security patches promptly.
Consider using a web application firewall (WAF) to filter malicious requests containing crafted TIFF files.