CVE-2008-5903 in xrdp
Summary
by MITRE
Array index error in the xrdp_bitmap_def_proc function in xrdp/funcs.c in xrdp 0.4.1 and earlier allows remote attackers to execute arbitrary code via vectors that manipulate the value of the edit_pos structure member.
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Analysis
by VulDB Data Team • 08/04/2021
The vulnerability described in CVE-2008-5903 represents a critical buffer overflow flaw within the xrdp remote desktop protocol implementation that affects versions 0.4.1 and earlier. This issue resides in the xrdp_bitmap_def_proc function located in the xrdp/funcs.c source file, where improper validation of input data leads to an array index error that can be exploited by remote attackers to gain arbitrary code execution capabilities. The vulnerability specifically targets the edit_pos structure member which controls the positioning and manipulation of bitmap data during remote desktop session processing, making it a significant threat to systems running vulnerable xrdp implementations.
The technical exploitation of this vulnerability occurs when an attacker manipulates the edit_pos structure member to cause an out-of-bounds array access within the xrdp_bitmap_def_proc function. This array index error allows malicious input to overwrite adjacent memory locations, potentially enabling attackers to inject and execute arbitrary code with the privileges of the xrdp service process. The flaw represents a classic case of improper input validation where the system fails to properly bounds-check the edit_pos value before using it as an array index, creating a path for attackers to control program execution flow through carefully crafted remote input sequences.
From an operational impact perspective, this vulnerability presents a severe threat to remote desktop infrastructure security as it allows remote code execution without requiring authentication, making it particularly dangerous for systems accessible over the internet. Organizations using vulnerable xrdp implementations face potential complete system compromise, data exfiltration, and lateral movement capabilities for attackers who can exploit this flaw. The vulnerability affects any system running xrdp versions 0.4.1 or earlier, including various Linux distributions and Unix-like systems that implement this remote desktop protocol stack, potentially impacting enterprise networks, cloud deployments, and remote access solutions.
The mitigation strategies for CVE-2008-5903 primarily focus on immediate version upgrades to patched releases of xrdp software, as the vulnerability is resolved through proper bounds checking and input validation mechanisms. System administrators should also implement network segmentation and access controls to limit exposure of xrdp services to untrusted networks, while monitoring for suspicious connection patterns and potential exploitation attempts. Additionally, the vulnerability aligns with CWE-129, which describes improper validation of array index bounds, and can be categorized under ATT&CK technique T1210 for exploitation of remote services, making it a target for both automated scanning tools and targeted attacks against remote desktop infrastructure. Organizations should also consider implementing intrusion detection systems that can identify patterns associated with this specific exploit vector and maintain comprehensive backup and recovery procedures to address potential compromise scenarios.