Title: cfingerd Buffer Oveflow Vulnerability
Severity: CRITICAL
Description:
There is a remotely exploitable buffer overflow in cfingerd 1.3.2, which ships with Debian GNU/Linux. The offending code is as follows:
int search_fake(char *username)
{
char parsed[80];
bzero(parsed, 80);
sscanf(username, "%[^.].%*[^\r\n]\r\n", parsed);
...
called from process_username(), that is called from main:
int main(int argc, char *argv[])
{
char username[100], syslog_str[200];
...
if (!emulated) {
if (!fgets(username, sizeof(username), stdin)) {
...
/* Check the finger information coming in and return its type */
un_type = process_username(username);
search_illegal() is called before search_fake(), so only legal characters [A-z0-9] can be used to exploit this vulnerability. The consequence is a remote root compromise.
Affected Products:
- Debian Linux 1.2.0
- Debian Linux 1.3.0
- Debian Linux 1.3.1
- Debian Linux 2.0.0
- Debian Linux 2.0.0r5
References:
- Debian GNU/Linux: Debian cfingerd Package Reference
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