CVE-2017-7875 in feh
Summary
by MITRE
In wallpaper.c in feh before v2.18.3, if a malicious client pretends to be the E17 window manager, it is possible to trigger an out-of-boundary heap write while receiving an IPC message. An integer overflow leads to a buffer overflow and/or a double free.
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Analysis
by VulDB Data Team • 08/23/2024
The vulnerability identified as CVE-2017-7875 affects the feh image viewer software version prior to v2.18.3, specifically within the wallpaper.c component responsible for handling inter-process communication messages. This flaw represents a critical security issue that arises from improper input validation and memory management practices when processing IPC messages from what appears to be the Enlightenment 17 (E17) window manager. The vulnerability manifests when a malicious client masquerades as the E17 window manager, exploiting a design flaw in the message handling mechanism that fails to properly validate message boundaries and buffer sizes.
The technical root cause of this vulnerability stems from an integer overflow condition that occurs during the processing of IPC messages received from the malicious client. When the feh application processes these messages, it fails to properly validate the length parameters associated with the incoming data, leading to an arithmetic overflow that subsequently results in an out-of-bounds heap write operation. This integer overflow condition creates a scenario where the application attempts to write data beyond the allocated memory boundaries, potentially overwriting adjacent heap memory regions. The vulnerability also introduces the possibility of a double free condition, which occurs when the same memory block is freed twice, leading to potential memory corruption and arbitrary code execution opportunities.
The operational impact of this vulnerability extends beyond simple memory corruption, as it provides a pathway for remote code execution when exploited by a malicious actor. An attacker capable of sending crafted IPC messages to a vulnerable feh instance can manipulate heap memory layout, potentially leading to privilege escalation or system compromise. The vulnerability is particularly concerning because it can be triggered through legitimate IPC mechanisms that feh expects to receive from window managers, making it difficult to distinguish between legitimate and malicious traffic. This attack vector represents a classic example of a buffer overflow vulnerability that can be exploited through IPC channels, aligning with common attack patterns documented in the attack mitigation framework.
The memory corruption resulting from this vulnerability creates multiple exploitation possibilities including heap spraying techniques and memory layout manipulation. The double free condition introduces additional complexity as it can be leveraged to create controlled memory corruption patterns that may be used to execute arbitrary code or bypass security mechanisms. From a compliance perspective, this vulnerability violates several security standards including those related to secure coding practices and memory safety, as outlined in the common weakness enumeration framework. The issue demonstrates poor input validation and memory management practices that should be addressed through proper bounds checking and integer overflow protection mechanisms.
Mitigation strategies for CVE-2017-7875 should focus on upgrading to feh version 2.18.3 or later, which contains the necessary patches to address the integer overflow and buffer overflow conditions. System administrators should also implement network segmentation and access controls to limit exposure to potentially malicious IPC traffic. The vulnerability highlights the importance of proper input validation and memory management in applications that handle inter-process communication, particularly those operating in multi-user environments where untrusted input sources may exist. Additionally, regular security audits of IPC mechanisms and memory handling code should be conducted to identify and remediate similar vulnerabilities before they can be exploited in production environments.