CVE-2008-1801 in rdesktop
Summary
by MITRE
Integer underflow in the iso_recv_msg function (iso.c) in rdesktop 1.5.0 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a Remote Desktop Protocol (RDP) request with a small length field.
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Analysis
by VulDB Data Team • 10/21/2024
The vulnerability identified as CVE-2008-1801 represents a critical integer underflow flaw within the rdesktop remote desktop client version 1.5.0. This issue resides in the iso_recv_msg function located in the iso.c source file, which handles the reception of Remote Desktop Protocol messages. The vulnerability arises when processing RDP requests where an attacker can manipulate the length field to values that cause integer underflow conditions during message processing. Such conditions occur when a signed integer operation results in a value that cannot be represented within the integer's range, leading to unexpected behavior in the application's memory management and control flow.
The technical exploitation of this vulnerability leverages the improper validation of message length fields within RDP protocol handling. When the iso_recv_msg function processes incoming data, it performs arithmetic operations on the length field without adequate bounds checking or overflow protection mechanisms. This allows an attacker to craft malicious RDP packets with intentionally small or negative length values that, when processed, trigger the integer underflow condition. The underflow can cause the application to allocate insufficient memory buffers or access invalid memory locations, ultimately resulting in application crashes or potentially allowing for arbitrary code execution depending on the specific memory corruption patterns that occur.
From an operational perspective, this vulnerability presents significant risk to systems utilizing rdesktop 1.5.0 for remote desktop connections. The remote nature of the attack means that any system running this vulnerable version could be compromised simply by accepting RDP connections from untrusted sources. The denial of service impact is immediate and certain, as any valid RDP connection attempt with the crafted malicious packet will cause the rdesktop client to crash and terminate. However, the potential for arbitrary code execution adds a more severe dimension to the threat, as successful exploitation could allow attackers to gain unauthorized control over the affected system. This vulnerability directly maps to CWE-191 Integer Underflow or Wraparound, which is categorized under the weakness type that describes situations where a signed integer is decremented below its minimum representable value.
The attack surface for this vulnerability extends beyond simple exploitation to include broader security implications for remote desktop infrastructure. The fact that this issue exists in a widely used open source remote desktop client means that numerous systems across various organizations could be potentially vulnerable, particularly those that have not updated to patched versions. The vulnerability demonstrates poor input validation practices that are consistent with common software security flaws, highlighting the need for comprehensive security testing and code review processes. Organizations using rdesktop should consider implementing network segmentation, access controls, and regular security updates to mitigate this risk. The vulnerability also aligns with ATT&CK technique T1210, which describes exploitation of remote services, and represents a classic example of how protocol-level vulnerabilities can lead to system compromise. Mitigation strategies include immediate patching of the rdesktop client to versions that address this integer underflow condition, implementing network-based protections such as firewalls that restrict RDP access, and conducting comprehensive vulnerability assessments to identify other potentially affected systems within the network infrastructure.