Hashcash: Possible heap overflow

1. Gentoo Linux Security Advisory

Advisory Reference	GLSA 200606-25 / hashcash
Release Date	June 26, 2006
Latest Revision	July 29, 2006: 02
Impact	high
Exploitable	remote

Package	Vulnerable versions	Unaffected versions	Architecture(s)
net-misc/hashcash	< 1.21	>= 1.21	All supported architectures

Related bugreports: #134960

Synopsis

A heap overflow vulnerability in the Hashcash utility could allow an attacker to execute arbitrary code.

2. Impact Information

Background

Hashcash is a utility for generating Hashcash tokens, a proof-of-work system to reduce the impact of spam.

Description

Andreas Seltenreich has reported a possible heap overflow in the array_push() function in hashcash.c, as a result of an incorrect amount of allocated memory for the "ARRAY" structure.

Impact

By sending malicious entries to the Hashcash utility, an attacker may be able to cause an overflow, potentially resulting in the execution of arbitrary code with the privileges of the user running the application.

3. Resolution Information

Workaround

There is no known workaround at this time.

Resolution

All Hashcash users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=net-misc/hashcash-1.21"

4. References

Updated June 26, 2006

Summary: This is a Gentoo Linux Security Advisory

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