CVE-2007-4396 in irssi
Summary
by MITRE
Multiple CRLF injection vulnerabilities in (1) ixmmsa.pl 0.3, (2) l33tmusic.pl 2.00, (3) mpg123.pl 0.01, (4) ogg123.pl 0.01, (5) xmms.pl 2.0, (6) xmms2.pl 1.1.3, and (7) xmmsinfo.pl 1.1.1.1 scripts for irssi before 0.8.11 allow user-assisted remote attackers to execute arbitrary IRC commands via CRLF sequences in the name of the song in a .mp3 file.
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Analysis
by VulDB Data Team • 09/07/2018
The vulnerability identified as CVE-2007-4396 represents a critical class of CRLF (Carriage Return Line Feed) injection flaws affecting multiple media-related scripts within the irssi IRC client ecosystem. These scripts including ixmmsa.pl 0.3, l33tmusic.pl 2.00, mpg123.pl 0.01, ogg123.pl 0.01, xmms.pl 2.0, xmms2.pl 1.1.3, and xmmsinfo.pl 1.1.1.1 operate as plugins that display song information within IRC channels. The flaw stems from inadequate input validation and sanitization of song metadata, specifically the song name field extracted from media files, which allows maliciously crafted CRLF sequences to be injected into the IRC protocol communication stream. This vulnerability is categorized under CWE-113 as "Improper Neutralization of CRLF Sequences in HTTP Headers" and aligns with ATT&CK technique T1071.004 for Application Layer Protocol: DNS, though the specific vector involves HTTP-like protocol manipulation within IRC contexts.
The technical exploitation of this vulnerability occurs when an attacker uploads or shares a media file containing specially crafted CRLF sequences within its metadata, particularly in the song title field. When irssi processes this metadata through the vulnerable scripts, the unescaped CRLF characters are interpreted as protocol terminators, enabling attackers to inject arbitrary IRC commands into the communication stream. This injection can occur in real-time as the song information is displayed in the IRC channel, potentially allowing for command execution, channel manipulation, or even remote code execution depending on the IRC server's configuration and the attacker's privileges. The vulnerability is particularly dangerous because it leverages legitimate user interaction patterns where users naturally share media information, making it difficult to distinguish between benign and malicious content.
The operational impact of CVE-2007-4396 extends beyond simple command injection, potentially enabling sophisticated attack vectors such as channel hijacking, spam distribution, or even persistent backdoor establishment within IRC networks. Attackers can manipulate the flow of information in channels, inject malicious commands that modify channel settings, or redirect communication to malicious endpoints. The vulnerability affects irssi versions prior to 0.8.11, representing a significant security gap in the software's input handling mechanisms. This flaw demonstrates the critical importance of proper input sanitization in protocol handling components, as the vulnerability allows attackers to exploit the trust relationship between IRC clients and servers. The attack requires only that a user view the metadata of a maliciously crafted media file, making it particularly effective in social engineering scenarios where users might be encouraged to share or play media files from untrusted sources.
Mitigation strategies for this vulnerability require immediate patching of irssi to version 0.8.11 or later, which includes proper input sanitization and CRLF sequence handling within the affected scripts. System administrators should implement strict input validation on all media metadata processing within IRC environments, particularly for plugins that handle external file information. Network monitoring should be enhanced to detect anomalous IRC command sequences that may indicate CRLF injection attempts. Additionally, users should be educated about the risks of sharing untrusted media files and the importance of verifying file integrity before playback. The fix addresses the root cause by implementing proper escaping of CRLF sequences in all protocol communication, preventing the injection of malicious command terminators. Organizations should also consider implementing network segmentation and access controls to limit the potential impact of successful exploitation, as the vulnerability can be leveraged to compromise entire IRC networks rather than individual client systems.