CVE-2008-1803 in rdesktop
Summary
by MITRE
Integer signedness error in the xrealloc function (rdesktop.c) in RDesktop 1.5.0 allows remote attackers to execute arbitrary code via unknown parameters that trigger a heap-based overflow. NOTE: the role of the channel_process function was not specified by the original researcher.
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Analysis
by VulDB Data Team • 08/10/2019
The vulnerability identified as CVE-2008-1803 represents a critical integer signedness error within the xrealloc function implementation in RDesktop version 1.5.0. This flaw resides in the rdesktop.c source file and constitutes a fundamental software engineering defect that creates conditions for heap-based buffer overflow exploitation. The vulnerability specifically manifests when processing unknown parameters that are passed to the system, creating a scenario where signed integer arithmetic operations can be manipulated to produce unexpected memory allocation behaviors. This type of error falls under the CWE-190 category of integer overflow and under CWE-122 for heap-based buffer overflow, representing a classic example of how improper integer handling can lead to memory corruption vulnerabilities.
The technical execution of this vulnerability occurs through the manipulation of parameters that flow through the channel_process function, although the exact role of this function remains unspecified by the original researcher. When the xrealloc function processes these malformed parameters, the signedness error causes the system to allocate insufficient memory space for the requested buffer operations. This insufficient allocation creates a condition where subsequent memory operations can overwrite adjacent heap memory regions, potentially allowing attackers to execute arbitrary code with the privileges of the affected process. The vulnerability operates at the memory management level, where integer overflow conditions translate into heap corruption that can be leveraged for code execution.
The operational impact of CVE-2008-1803 extends beyond simple remote code execution to encompass potential privilege escalation and system compromise scenarios. Attackers exploiting this vulnerability can manipulate the memory layout of the RDesktop application to redirect execution flow, inject malicious code, or overwrite critical system structures. The heap-based nature of the overflow means that the attack surface includes not only the immediate application memory but also potentially adjacent memory regions that could contain sensitive data or control structures. This vulnerability represents a significant threat in environments where RDesktop is used for remote desktop access, as it allows unauthorized remote attackers to gain control over systems running vulnerable versions of the software.
Mitigation strategies for CVE-2008-1803 should focus on immediate version updates to patched releases of RDesktop that address the integer signedness error in the xrealloc function. System administrators should implement network segmentation and access controls to limit exposure of vulnerable RDesktop instances to untrusted networks. The vulnerability aligns with ATT&CK technique T1059 for command and scripting interpreter and T1068 for exploit for privilege escalation, making defensive measures such as application whitelisting and memory protection mechanisms particularly valuable. Additionally, implementing proper input validation and bounds checking in the affected code sections would prevent the integer overflow conditions that enable this vulnerability, while regular security audits of memory management functions can help identify similar issues in other applications.