Executive brief
Base64 Decoder is a utility used to convert encoded text back into its original file format, often used for extracting email attachments. A security flaw in version 1.1.2 allows an attacker to take control of a computer if they can convince a user to process a specially crafted, malicious input file. This could result in the attacker gaining full access to the system, potentially leading to data theft or the installation of malware.
Technical details
A stack-based buffer overflow exists in Base64 Decoder 1.1.2 due to improper bounds checking during the processing of input data. A local attacker can exploit this by providing a specially crafted input file that triggers a Structured Exception Handler (SEH) overwrite. By overwriting the SEH chain with a POP-POP-RET gadget address and utilizing an egghunter payload, the attacker can redirect execution flow to arbitrary shellcode. The vulnerability is categorized as CWE-787 (Out-of-bounds Write) and has been demonstrated on Windows platforms. No official patch is currently noted, though the software is legacy.
Affected products
- 4mhz Base64 Decoder 1.1.2
Timeline
- 2007-08-21: other: Version 1.1.2 released
- 2019-03-28: disclosed: Exploit code published on Exploit-DB
- 2026-03-24: advisory: NVD/VulnCheck advisory published