CVE-2006-6909 in Edbrowse
Summary
by MITRE
Stack-based buffer overflow in http.c in Karl Dahlke Edbrowse (aka Command line editor browser) 3.1.3 allows remote attackers to execute arbitrary code by operating an FTP server that sends directory listings with (1) long user names or (2) long group names.
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Analysis
by VulDB Data Team • 08/13/2018
The vulnerability identified as CVE-2006-6909 represents a critical stack-based buffer overflow in Karl Dahlke Edbrowse version 3.1.3, specifically within the http.c component. This flaw manifests when the application processes directory listings from FTP servers, creating a remote code execution vector that adversaries can exploit to gain unauthorized system access. The vulnerability stems from insufficient input validation and bounds checking in the handling of user and group name fields within FTP directory listings, which are commonly used in Unix-based file transfer protocols.
The technical implementation of this vulnerability occurs through the manipulation of FTP directory listing responses that contain excessively long user or group names. When Edbrowse processes these malformed directory entries, the application fails to properly validate the length of the username or group name fields, leading to a buffer overflow condition on the stack. This overflow corrupts adjacent memory locations including return addresses and control data, allowing attackers to redirect execution flow to malicious code injected into the buffer. The vulnerability specifically targets the stack memory allocation pattern where fixed-size buffers are used to store user-provided data without adequate bounds checking, a common weakness classified under CWE-121 Stack-based Buffer Overflow.
From an operational perspective, this vulnerability presents a significant risk to systems running Edbrowse version 3.1.3 that connect to untrusted FTP servers or when attackers compromise FTP infrastructure to deliver malicious directory listings. The remote exploitation capability means that adversaries do not require local access to the target system, making this vulnerability particularly dangerous in networked environments where FTP connectivity is common. The attack vector aligns with ATT&CK technique T1190 for Exploit Public-Facing Application, as it targets a network-facing component that processes external data from FTP servers. The vulnerability can be exploited through various means including compromised FTP servers, man-in-the-middle attacks on FTP connections, or by hosting malicious FTP servers specifically designed to deliver the exploit payload.
The impact of successful exploitation includes complete system compromise, allowing attackers to execute arbitrary code with the privileges of the Edbrowse process, typically running with user-level permissions but potentially escalating to higher privileges depending on system configuration. This vulnerability demonstrates the importance of input validation in network applications and highlights the risks associated with processing untrusted data from remote sources. Organizations should consider implementing network segmentation to limit FTP access, using secure FTP implementations with proper input sanitization, and applying the vendor-provided patch or upgrading to a newer version of Edbrowse that addresses this buffer overflow condition. The vulnerability also underscores the need for proper memory safety practices in legacy applications and the importance of regular security assessments of network-facing components that process external data streams.