CVE-2009-1095 in JRE
Summary
by MITRE
Integer overflow in unpack200 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 a JAR file with crafted Pack200 headers.
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Analysis
by VulDB Data Team • 08/09/2021
The vulnerability identified as CVE-2009-1095 represents a critical integer overflow flaw within the unpack200 utility of Oracle Java SE Development Kit and Runtime Environment. This issue affects versions prior to JDK/JRE 5.0 Update 17 and 6 Update 12, creating a significant security risk that can be exploited remotely through maliciously crafted JAR files. The vulnerability resides in the Pack200 unpacking process which is used to decompress Java Archive files that have been compressed using the Pack200 format. When the unpack200 utility processes malformed Pack200 headers, it fails to properly validate integer values, leading to arithmetic overflow conditions that can result in unpredictable behavior.
The technical flaw manifests when the unpack200 utility encounters crafted Pack200 headers containing oversized integer values that exceed the maximum representable value for the target integer type. This integer overflow condition can cause the application to allocate insufficient memory buffers or trigger incorrect pointer arithmetic during the decompression process. The vulnerability is classified under CWE-190 as an integer overflow error, specifically involving signed integer overflow that occurs during the processing of compressed archive data. The flaw allows attackers to manipulate the memory allocation and buffer handling mechanisms within the Java runtime environment, potentially leading to memory corruption that can be leveraged for privilege escalation or arbitrary code execution.
The operational impact of this vulnerability extends beyond simple file access restrictions, as it provides remote attackers with the capability to execute arbitrary code on affected systems. Attackers can craft malicious JAR files with specially designed Pack200 headers that trigger the integer overflow condition when processed by the unpack200 utility. This exploitation vector is particularly dangerous because it can be triggered through legitimate Java application workflows where JAR files are automatically decompressed or processed. The vulnerability affects both client-side Java applications and server-side environments where Java applications may process user-supplied JAR files, potentially enabling attackers to compromise entire systems or gain unauthorized access to sensitive data. According to ATT&CK framework, this vulnerability maps to T1059.007 for execution through Java and T1566 for initial access via malicious JAR files.
Mitigation strategies for CVE-2009-1095 primarily focus on immediate patching of affected Java installations to the latest available versions that contain the necessary security fixes. Organizations should prioritize updating their JDK/JRE installations to versions that have addressed this integer overflow condition in the unpack200 utility. Additionally, implementing strict input validation and sanitization measures for JAR file processing can help reduce the attack surface. Network-level controls such as firewall rules that restrict access to Java application endpoints and content filtering solutions that scan JAR files for malicious headers should be deployed. System administrators should also consider disabling Pack200 functionality in Java applications when it is not required, as this reduces the potential attack vectors. Regular security assessments and vulnerability scanning should be conducted to identify any remaining unpatched systems, while application whitelisting solutions can provide additional protection by restricting execution of unauthorized Java applications that might process untrusted JAR files. The vulnerability serves as a reminder of the importance of proper integer overflow protection in security-critical code paths that handle user-supplied data.