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added a security check for extracting zip / tnef attachments

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SJ 2015-03-16 13:06:57 +01:00
parent 4c489d1a47
commit e46b1e9f64
1 changed files with 21 additions and 8 deletions
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29
src/extract.c
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@ -95,10 +95,18 @@ int extract_opendocument(struct session_data *sdata, struct _state *state, char
}
int is_safe_filetype(char *s){
/*
* a safe filename contains the following characters:
* space ( ),
* dash (-),
* dot (.),
* underscore (_)
* numbers and letters
*/
int is_safe_filename(char *s){
for(; *s; s++){
if(*s != 46 && !isalnum(*s)){
if(*s != 32 && *s != 45 && *s != 46 && *s != 95 && !isalnum(*s)){
return 0;
}
}
@ -108,7 +116,7 @@ int is_safe_filetype(char *s){
int unzip_file(struct session_data *sdata, struct _state *state, char *filename, int *rec, struct __config *cfg){
int errorp, i=0, len=0, fd, safe_extension=0;
int errorp, i=0, len=0, fd, safe_to_process=0;
char *p, extracted_filename[SMALLBUFSIZE], buf[MAXBUFSIZE];
struct zip *z;
struct zip_stat sb;
@ -128,13 +136,13 @@ int unzip_file(struct session_data *sdata, struct _state *state, char *filename,
if(ZIP_EM_NONE == sb.encryption_method) {
p = strrchr(sb.name, '.');
safe_extension = 0;
safe_to_process = 0;
if(p) safe_extension = is_safe_filetype(p);
if(p) safe_to_process = is_safe_filename(p);
if(safe_extension == 0) syslog(LOG_INFO, "%s: invalid filename in zip: '%s'", sdata->ttmpfile, (char*)sb.name);
if(safe_to_process == 0) syslog(LOG_INFO, "%s: invalid filename in zip: '%s'", sdata->ttmpfile, (char*)sb.name);
if((int)sb.size > 0 && safe_extension == 1 && strcmp(get_attachment_extractor_by_filename((char*)sb.name), "other")){
if((int)sb.size > 0 && safe_to_process == 1 && strcmp(get_attachment_extractor_by_filename((char*)sb.name), "other")){
snprintf(extracted_filename, sizeof(extracted_filename)-1, "%s-%d-%d%s", sdata->ttmpfile, *rec, i, p);
@ -203,9 +211,14 @@ int extract_tnef(struct session_data *sdata, struct _state *state, char *filenam
else {
while(n--){
if(strcmp(namelist[n]->d_name, ".") && strcmp(namelist[n]->d_name, "..")){
snprintf(buf, sizeof(buf)-1, "%s/%s", tmpdir, namelist[n]->d_name);
extract_attachment_content(sdata, state, buf, get_attachment_extractor_by_filename(buf), &rec, cfg);
if(is_safe_filename(namelist[n]->d_name) == 1){
extract_attachment_content(sdata, state, buf, get_attachment_extractor_by_filename(buf), &rec, cfg);
} else {
syslog(LOG_INFO, "%s: not a safe file to process: '%s'", sdata->ttmpfile, namelist[n]->d_name);
}
unlink(buf);
}