CVE-2009-1099 in JRE
Summary
by MITRE
Integer signedness error in Java SE Development Kit (JDK) and Java Runtime Environment (JRE) 5.0 Update 17 and earlier, and 6 Update 12 and earlier, allows remote attackers to access files or execute arbitrary code via crafted glyph descriptions in a Type1 font, which bypasses a signed comparison and triggers a buffer overflow.
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Analysis
by VulDB Data Team • 08/09/2021
The vulnerability identified as CVE-2009-1099 represents a critical integer signedness error within the Java SE Development Kit and Runtime Environment implementations. This flaw exists in versions prior to JDK/JRE 5.0 Update 17 and 6.0 Update 12, where the processing of Type1 font files contains a fundamental flaw in how integer values are handled during buffer operations. The vulnerability stems from improper handling of signed versus unsigned integer comparisons during font rendering operations, creating a condition where maliciously crafted glyph descriptions can manipulate the program flow.
The technical implementation of this vulnerability involves a buffer overflow scenario that occurs when the Java runtime processes Type1 font files containing specially crafted glyph data. During the parsing of font metrics and glyph descriptions, the system performs a signed comparison that fails to properly validate the size parameters of font data structures. This signedness error allows attackers to manipulate the comparison logic such that a buffer overflow condition is triggered when the system attempts to allocate or copy data into memory buffers. The flaw specifically affects the font rendering subsystem within Java's graphics processing pipeline, where Type1 fonts are processed through the Java 2D API.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass full remote code execution capabilities. Attackers can leverage this vulnerability to execute arbitrary code on affected systems by crafting malicious Type1 font files that, when processed by the vulnerable Java runtime, trigger the buffer overflow condition. The vulnerability enables unauthorized file access patterns and can potentially allow attackers to bypass security restrictions within the Java sandbox environment. This represents a significant threat vector for web-based attacks where users might unknowingly download and process malicious font files through Java applets or web applications that utilize font rendering functionality.
The vulnerability aligns with CWE-190, which describes integer overflow and underflow conditions, and specifically relates to CWE-129, which addresses improper validation of array indices. From an ATT&CK framework perspective, this vulnerability maps to techniques involving execution through libraries and privilege escalation through exploitation of software vulnerabilities. The attack vector typically involves social engineering to deliver malicious font files through web browsers or email attachments, with the Java runtime executing the malicious code when the font is rendered. Mitigation strategies include immediate patching of affected Java versions, implementing strict font file validation policies, and restricting Java applet execution in web browsers. Organizations should also consider implementing network-level controls to block suspicious font file types and establish monitoring for unusual font processing activities within their systems.