| From ee45a34907ffeb5fd95b0513040d8491d565b663 Mon Sep 17 00:00:00 2001 |
| From: Eldar Zaitov <kyprizel@volema.com> |
| Date: Wed, 30 Jan 2013 23:22:27 +0100 |
| Subject: [PATCH] Curl_sasl_create_digest_md5_message: fix buffer overflow |
| |
| When negotiating SASL DIGEST-MD5 authentication, the function |
| Curl_sasl_create_digest_md5_message() uses the data provided from the |
| server without doing the proper length checks and that data is then |
| appended to a local fixed-size buffer on the stack. |
| |
| This vulnerability can be exploited by someone who is in control of a |
| server that a libcurl based program is accessing with POP3, SMTP or |
| IMAP. For applications that accept user provided URLs, it is also |
| thinkable that a malicious user would feed an application with a URL to |
| a server hosting code targetting this flaw. |
| |
| Bug: http://curl.haxx.se/docs/adv_20130206.html |
| --- |
| lib/curl_sasl.c | 23 ++++++----------------- |
| 1 file changed, 6 insertions(+), 17 deletions(-) |
| |
| diff --git a/lib/curl_sasl.c b/lib/curl_sasl.c |
| index 57116b6..d07387d 100644 |
| --- a/lib/curl_sasl.c |
| +++ b/lib/curl_sasl.c |
| @@ -346,9 +346,7 @@ CURLcode Curl_sasl_create_digest_md5_message(struct SessionHandle *data, |
| snprintf(&HA1_hex[2 * i], 3, "%02x", digest[i]); |
| |
| /* Prepare the URL string */ |
| - strcpy(uri, service); |
| - strcat(uri, "/"); |
| - strcat(uri, realm); |
| + snprintf(uri, sizeof(uri), "%s/%s", service, realm); |
| |
| /* Calculate H(A2) */ |
| ctxt = Curl_MD5_init(Curl_DIGEST_MD5); |
| @@ -392,20 +390,11 @@ CURLcode Curl_sasl_create_digest_md5_message(struct SessionHandle *data, |
| for(i = 0; i < MD5_DIGEST_LEN; i++) |
| snprintf(&resp_hash_hex[2 * i], 3, "%02x", digest[i]); |
| |
| - strcpy(response, "username=\""); |
| - strcat(response, userp); |
| - strcat(response, "\",realm=\""); |
| - strcat(response, realm); |
| - strcat(response, "\",nonce=\""); |
| - strcat(response, nonce); |
| - strcat(response, "\",cnonce=\""); |
| - strcat(response, cnonce); |
| - strcat(response, "\",nc="); |
| - strcat(response, nonceCount); |
| - strcat(response, ",digest-uri=\""); |
| - strcat(response, uri); |
| - strcat(response, "\",response="); |
| - strcat(response, resp_hash_hex); |
| + snprintf(response, sizeof(response), |
| + "username=\"%s\",realm=\"%s\",nonce=\"%s\"," |
| + "cnonce=\"%s\",nc=\"%s\",digest-uri=\"%s\",response=%s", |
| + userp, realm, nonce, |
| + cnonce, nonceCount, uri, resp_hash_hex); |
| |
| /* Base64 encode the reply */ |
| return Curl_base64_encode(data, response, 0, outptr, outlen); |
| -- |
| 1.7.10.4 |
| |