CVE-2018-8784 in FreeRDP
Summary
by MITRE
FreeRDP prior to version 2.0.0-rc4 contains a Heap-Based Buffer Overflow in function zgfx_decompress_segment() that results in a memory corruption and probably even a remote code execution.
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Analysis
by VulDB Data Team • 06/12/2023
The vulnerability identified as CVE-2018-8784 affects FreeRDP versions prior to 2.0.0-rc4 and represents a critical heap-based buffer overflow within the zgfx_decompress_segment() function. This flaw exists in the remote desktop protocol implementation that handles compressed graphics data during RDP sessions. The vulnerability stems from insufficient input validation and boundary checking when processing compressed graphics segments, creating an opportunity for malicious actors to manipulate memory structures through crafted compressed data payloads.
The technical implementation of this vulnerability involves the zgfx_decompress_segment() function failing to properly validate the size of decompressed data against allocated buffer boundaries. When FreeRDP processes compressed graphics data from a remote RDP server, the decompression routine does not adequately verify that the decompressed output will fit within the pre-allocated memory buffer. This allows attackers to provide maliciously crafted compressed data that exceeds buffer limits, causing memory corruption that can be exploited to execute arbitrary code. The vulnerability operates at the memory management level and directly impacts the application's heap allocation strategy.
From an operational perspective, this vulnerability presents significant risk to organizations relying on FreeRDP for remote desktop connections. Attackers can potentially achieve remote code execution by establishing an RDP connection to a vulnerable system and sending specially crafted compressed graphics data. The impact extends beyond simple memory corruption as the vulnerability can be leveraged for privilege escalation, system compromise, and lateral movement within network environments. This makes it particularly dangerous for enterprise environments where RDP is commonly used for remote administration and access to sensitive systems.
The vulnerability aligns with CWE-121, heap-based buffer overflow, and maps to several ATT&CK techniques including T1059 for command and control, T1074 for data staging, and T1566 for credential harvesting through remote access. Organizations should prioritize immediate patching of all FreeRDP installations to version 2.0.0-rc4 or later, as this represents a critical security remediation. Additional mitigations include network segmentation to limit RDP access, implementation of network monitoring to detect anomalous compressed data patterns, and deployment of intrusion detection systems to identify potential exploitation attempts. The vulnerability demonstrates the importance of proper memory management in network protocol implementations and highlights the need for rigorous input validation in graphics compression routines.